diff --git a/contrib/telnet/arpa/telnet.h b/contrib/telnet/arpa/telnet.h
index d7942671db31..b8d3856727b8 100644
--- a/contrib/telnet/arpa/telnet.h
+++ b/contrib/telnet/arpa/telnet.h
@@ -214,7 +214,7 @@ char *telopts[NTELOPTS+1] = {
 #define	NSLC		30
 
 /*
- * For backwards compatability, we define SLC_NAMES to be the
+ * For backwards compatibility, we define SLC_NAMES to be the
  * list of names if SLC_NAMES is not defined.
  */
 #define	SLC_NAMELIST	"0", "SYNCH", "BRK", "IP", "AO", "AYT", "EOR", \
diff --git a/crypto/telnet/arpa/telnet.h b/crypto/telnet/arpa/telnet.h
index d7942671db31..b8d3856727b8 100644
--- a/crypto/telnet/arpa/telnet.h
+++ b/crypto/telnet/arpa/telnet.h
@@ -214,7 +214,7 @@ char *telopts[NTELOPTS+1] = {
 #define	NSLC		30
 
 /*
- * For backwards compatability, we define SLC_NAMES to be the
+ * For backwards compatibility, we define SLC_NAMES to be the
  * list of names if SLC_NAMES is not defined.
  */
 #define	SLC_NAMELIST	"0", "SYNCH", "BRK", "IP", "AO", "AYT", "EOR", \
diff --git a/lib/libstand/ext2fs.c b/lib/libstand/ext2fs.c
index 1303255486ae..6c05cf5a5cfa 100644
--- a/lib/libstand/ext2fs.c
+++ b/lib/libstand/ext2fs.c
@@ -199,7 +199,7 @@ struct ext2fs_disk {
 	u_int16_t	fd_nblkgrp;	/* block group # of superblock */
 	u_int32_t	fd_fcompat;	/* compatible features */
 	u_int32_t	fd_fincompat;	/* incompatible features */
-	u_int32_t	fd_frocompat;	/* read-only compatabilties */
+	u_int32_t	fd_frocompat;	/* read-only compatibilties */
 	u_int8_t	fd_uuid[16];	/* volume uuid */
 	char 		fd_volname[16];	/* volume name */
 	char 		fd_fsmnt[64];	/* name last mounted on */
diff --git a/lib/libz/minigzip.c b/lib/libz/minigzip.c
index e8a61b13e711..7c7246415358 100644
--- a/lib/libz/minigzip.c
+++ b/lib/libz/minigzip.c
@@ -300,7 +300,7 @@ int main(argc, argv)
 
     while (argc > 0) {
       if (strcmp(*argv, "-c") == 0)
-	; /* Just for compatability with gzip */
+	; /* Just for compatibility with gzip */
       else if (strcmp(*argv, "-d") == 0)
 	uncompr = 1;
       else if (strcmp(*argv, "-f") == 0)
diff --git a/libexec/rshd/rshd.c b/libexec/rshd/rshd.c
index 50ecad22dafc..20f794a17411 100644
--- a/libexec/rshd/rshd.c
+++ b/libexec/rshd/rshd.c
@@ -131,7 +131,7 @@ main(argc, argv)
 	while ((ch = getopt(argc, argv, OPTIONS)) != -1)
 		switch (ch) {
 		case 'a':
-			/* ignored for compatability */
+			/* ignored for compatibility */
 			break;
 		case 'l':
 			__check_rhosts_file = 0;
diff --git a/release/texts/alpha/RELNOTES.TXT b/release/texts/alpha/RELNOTES.TXT
index f17d44d1770f..5ab3deafda7b 100644
--- a/release/texts/alpha/RELNOTES.TXT
+++ b/release/texts/alpha/RELNOTES.TXT
@@ -544,7 +544,7 @@ mergemaster(8) has gained some new features, has been cleaned up
 somewhat, and is now more cross-platform friendly.
 
 The compiler chain now uses the FSF-supplied C/C++ runtime
-initialization code.  This change brings about better compatability
+initialization code.  This change brings about better compatibility
 with code generated from the various egcs and gcc ports, as well as
 the stock public FSF source. [MERGED]
 
diff --git a/release/texts/i386/RELNOTES.TXT b/release/texts/i386/RELNOTES.TXT
index b4cf9d6862ef..69f192eb59b6 100644
--- a/release/texts/i386/RELNOTES.TXT
+++ b/release/texts/i386/RELNOTES.TXT
@@ -642,7 +642,7 @@ mergemaster(8) has gained some new features, has been cleaned up
 somewhat, and is now more cross-platform friendly.
 
 The compiler chain now uses the FSF-supplied C/C++ runtime
-initialization code.  This change brings about better compatability
+initialization code.  This change brings about better compatibility
 with code generated from the various egcs and gcc ports, as well as
 the stock public FSF source. [MERGED]
 
diff --git a/sys/conf/files.i386 b/sys/conf/files.i386
index a6537e175125..845e85abc69f 100644
--- a/sys/conf/files.i386
+++ b/sys/conf/files.i386
@@ -227,7 +227,7 @@ i386/isa/intr_machdep.c		standard
 i386/isa/ithread.c		standard
 i386/isa/isa.c			optional	isa
 i386/isa/isa_compat.c		optional	isa compat_oldisa	\
-	warning "Old ISA driver compatability shims present."
+	warning "Old ISA driver compatibility shims present."
 i386/isa/isa_dma.c		optional	isa
 i386/isa/istallion.c		optional	stli
 i386/isa/loran.c		optional	loran
diff --git a/sys/conf/files.pc98 b/sys/conf/files.pc98
index ded0df120817..4ffce8ccfa3c 100644
--- a/sys/conf/files.pc98
+++ b/sys/conf/files.pc98
@@ -220,7 +220,7 @@ i386/isa/intr_machdep.c		standard
 i386/isa/ithread.c		standard
 i386/isa/isa.c			optional	isa
 i386/isa/isa_compat.c		optional	isa compat_oldisa	\
-	warning "Old ISA driver compatability shims present."
+	warning "Old ISA driver compatibility shims present."
 i386/isa/istallion.c		optional	stli
 i386/isa/loran.c		optional	loran
 i386/isa/matcd/matcd.c		count		matcd
diff --git a/sys/dev/dpt/dpt.h b/sys/dev/dpt/dpt.h
index 6d6230e75014..8798f7650983 100644
--- a/sys/dev/dpt/dpt.h
+++ b/sys/dev/dpt/dpt.h
@@ -904,7 +904,7 @@ typedef struct dpt_ccb {
 } dpt_ccb_t;
 
 /*
- * This is provided for compatability with UnixWare only.
+ * This is provided for compatibility with UnixWare only.
  * Some of the fields may be bogus.
  * Others may have a totally different meaning.
  */
diff --git a/sys/i386/include/if_wl_wavelan.h b/sys/i386/include/if_wl_wavelan.h
index 63c5a93f7d9b..ad7d28e65e6b 100644
--- a/sys/i386/include/if_wl_wavelan.h
+++ b/sys/i386/include/if_wl_wavelan.h
@@ -112,7 +112,7 @@
 #define WLPSA_UNIMAC		0x10	/* Universal MAC address */
 #define WLPSA_LOCALMAC		0x16	/* Locally configured MAC address */
 #define WLPSA_MACSEL		0x1c	/* MAC selector */
-#define WLPSA_COMPATNO		0x1d	/* compatability number */
+#define WLPSA_COMPATNO		0x1d	/* compatibility number */
 #define WLPSA_THRESH		0x1e	/* RF modem threshold preset */
 #define WLPSA_FEATSEL		0x1f	/* feature select */
 #define WLPSA_SUBBAND		0x20	/* subband selector */
diff --git a/sys/i386/isa/isa_compat.c b/sys/i386/isa/isa_compat.c
index 8dd1bece49ed..099e0b9fb0de 100644
--- a/sys/i386/isa/isa_compat.c
+++ b/sys/i386/isa/isa_compat.c
@@ -245,7 +245,7 @@ isa_compat_attach(device_t dev)
 			printf("isa_compat_attach: failed to setup intr: %d\n",
 			       error);
 	}
-	device_printf(dev, "driver is using old-style compatability shims\n");
+	device_printf(dev, "driver is using old-style compatibility shims\n");
 	return 0;
 }
 
diff --git a/sys/i386/isa/istallion.c b/sys/i386/isa/istallion.c
index 36932b90177c..61b7a5087060 100644
--- a/sys/i386/isa/istallion.c
+++ b/sys/i386/isa/istallion.c
@@ -121,7 +121,7 @@
 
 /*
  *	Define the important minor number break down bits. These have been
- *	chosen to be "compatable" with the standard sio driver minor numbers.
+ *	chosen to be "compatible" with the standard sio driver minor numbers.
  *	Extra high bits are used to distinguish between boards and also for
  *	really high port numbers (> 32).
  */
@@ -1202,7 +1202,7 @@ STATIC int stliioctl(dev_t dev, unsigned long cmd, caddr_t data, int flag,
 	}
 
 /*
- *	Deal with 4.3 compatability issues if we have too...
+ *	Deal with 4.3 compatibility issues if we have too...
  */
 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
 	if (1) {
diff --git a/sys/i386/isa/stallion.c b/sys/i386/isa/stallion.c
index 2d35463c202e..73c2ce19b387 100644
--- a/sys/i386/isa/stallion.c
+++ b/sys/i386/isa/stallion.c
@@ -117,7 +117,7 @@ static unsigned int	stl_irqshared = 0;
 
 /*
  *	Define the important minor number break down bits. These have been
- *	chosen to be "compatable" with the standard sio driver minor numbers.
+ *	chosen to be "compatible" with the standard sio driver minor numbers.
  *	Extra high bits are used to distinguish between boards.
  */
 #define	STL_CALLOUTDEV		0x80
@@ -990,7 +990,7 @@ STATIC int stlioctl(dev_t dev, unsigned long cmd, caddr_t data, int flag,
 	}
 
 /*
- *	Deal with 4.3 compatability issues if we have too...
+ *	Deal with 4.3 compatibility issues if we have too...
  */
 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
 	if (1) {
diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c
index a5b505fbd290..7238499722b0 100644
--- a/sys/kern/kern_prot.c
+++ b/sys/kern/kern_prot.c
@@ -372,7 +372,7 @@ setpgid(curp, uap)
 
 /*
  * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD
- * compatable.  It says that setting the uid/gid to euid/egid is a special
+ * compatible.  It says that setting the uid/gid to euid/egid is a special
  * case of "appropriate privilege".  Once the rules are expanded out, this
  * basically means that setuid(nnn) sets all three id's, in all permitted
  * cases unless _POSIX_SAVED_IDS is enabled.  In that case, setuid(getuid())
@@ -402,7 +402,7 @@ setuid(p, uap)
 	 *
 	 * Note that setuid(geteuid()) is a special case of 
 	 * "appropriate privileges" in appendix B.4.2.2.  We need
-	 * to use this clause to be compatable with traditional BSD
+	 * to use this clause to be compatible with traditional BSD
 	 * semantics.  Basically, it means that "setuid(xx)" sets all
 	 * three id's (assuming you have privs).
 	 *
@@ -519,7 +519,7 @@ setgid(p, uap)
 	 *
 	 * Note that setgid(getegid()) is a special case of
 	 * "appropriate privileges" in appendix B.4.2.2.  We need
-	 * to use this clause to be compatable with traditional BSD
+	 * to use this clause to be compatible with traditional BSD
 	 * semantics.  Basically, it means that "setgid(xx)" sets all
 	 * three id's (assuming you have privs).
 	 *
diff --git a/sys/net/if.h b/sys/net/if.h
index 8afeac026853..bcc10adaf28a 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -39,7 +39,7 @@
 
 /*
  * <net/if.h> does not depend on <sys/time.h> on most other systems.  This
- * helps userland compatability.  (struct timeval ifi_lastchange)
+ * helps userland compatibility.  (struct timeval ifi_lastchange)
  */
 #ifndef _KERNEL
 #include <sys/time.h>
@@ -109,7 +109,7 @@ struct if_data {
  */
 struct if_msghdr {
 	u_short	ifm_msglen;	/* to skip over non-understood messages */
-	u_char	ifm_version;	/* future binary compatability */
+	u_char	ifm_version;	/* future binary compatibility */
 	u_char	ifm_type;	/* message type */
 	int	ifm_addrs;	/* like rtm_addrs */
 	int	ifm_flags;	/* value of if_flags */
@@ -123,7 +123,7 @@ struct if_msghdr {
  */
 struct ifa_msghdr {
 	u_short	ifam_msglen;	/* to skip over non-understood messages */
-	u_char	ifam_version;	/* future binary compatability */
+	u_char	ifam_version;	/* future binary compatibility */
 	u_char	ifam_type;	/* message type */
 	int	ifam_addrs;	/* like rtm_addrs */
 	int	ifam_flags;	/* value of ifa_flags */
@@ -137,7 +137,7 @@ struct ifa_msghdr {
  */
 struct ifma_msghdr {
 	u_short	ifmam_msglen;	/* to skip over non-understood messages */
-	u_char	ifmam_version;	/* future binary compatability */
+	u_char	ifmam_version;	/* future binary compatibility */
 	u_char	ifmam_type;	/* message type */
 	int	ifmam_addrs;	/* like rtm_addrs */
 	int	ifmam_flags;	/* value of ifa_flags */
diff --git a/sys/netinet6/nd6.h b/sys/netinet6/nd6.h
index be1264d6d8d0..26f58b50a991 100644
--- a/sys/netinet6/nd6.h
+++ b/sys/netinet6/nd6.h
@@ -197,7 +197,7 @@ struct nd_prefix {
  */
 struct inet6_ndpr_msghdr {
 	u_short	inpm_msglen;	/* to skip over non-understood messages */
-	u_char	inpm_version;	/* future binary compatability */
+	u_char	inpm_version;	/* future binary compatibility */
 	u_char	inpm_type;	/* message type */
 	struct in6_addr inpm_prefix;
 	u_long	prm_vltim;
diff --git a/sys/sys/poll.h b/sys/sys/poll.h
index 9358c122226a..bacef36e2002 100644
--- a/sys/sys/poll.h
+++ b/sys/sys/poll.h
@@ -32,7 +32,7 @@
 #define	_SYS_POLL_H_
 
 /*
- * This file is intended to be compatable with the traditional poll.h.
+ * This file is intended to be compatible with the traditional poll.h.
  */
 
 /*
diff --git a/sys/sys/time.h b/sys/sys/time.h
index 74274f824bab..16b1249baed7 100644
--- a/sys/sys/time.h
+++ b/sys/sys/time.h
@@ -120,7 +120,7 @@ struct timezone {
 
 #endif /* _KERNEL */
 
-#ifndef _KERNEL			/* NetBSD/OpenBSD compatable interfaces */
+#ifndef _KERNEL			/* NetBSD/OpenBSD compatible interfaces */
 
 #define	timerclear(tvp)		(tvp)->tv_sec = (tvp)->tv_usec = 0
 #define	timerisset(tvp)		((tvp)->tv_sec || (tvp)->tv_usec)
diff --git a/usr.bin/brandelf/brandelf.c b/usr.bin/brandelf/brandelf.c
index 3ae4bdf7d0e2..ec591e687204 100644
--- a/usr.bin/brandelf/brandelf.c
+++ b/usr.bin/brandelf/brandelf.c
@@ -67,7 +67,7 @@ main(int argc, char **argv)
 		switch (ch) {
 		case 'f':
 			if (change)
-				errx(1, "f option incompatable with t option");
+				errx(1, "f option incompatible with t option");
 			force = 1;
 			type = atoi(optarg);
 			if (errno == ERANGE || type < 0 || type > 255) {
@@ -85,7 +85,7 @@ main(int argc, char **argv)
 			break;
 		case 't':
 			if (force)
-				errx(1, "t option incompatable with f option");
+				errx(1, "t option incompatible with f option");
 			change = 1;
 			strtype = optarg;
 			break;
diff --git a/usr.bin/doscmd/emuint.c b/usr.bin/doscmd/emuint.c
index 750a6f9ee06a..8e321c0cbcf2 100644
--- a/usr.bin/doscmd/emuint.c
+++ b/usr.bin/doscmd/emuint.c
@@ -92,14 +92,14 @@ emuint(regcontext_t *REGS)
 
             /* 
              * XXX
-             * temporary backwards compatability with instbsdi.exe
+             * temporary backwards compatibility with instbsdi.exe
              * remove after a while.
              */
             fprintf(stderr, "***\n*** WARNING - unknown emuint function\n");
             fprintf(stderr, "*** Continuing; assuming instbsdi redirector.\n");
             fprintf(stderr, "*** Please install the new redirector");
             fprintf(stderr, " `redir.com' as soon as possible.\n");
-            fprintf(stderr, "*** This compatability hack is not permanent.\n");
+            fprintf(stderr, "*** This compatibility hack is not permanent.\n");
             fprintf(stderr, "***\n");
             PUSH(R_AX, REGS);
             R_BX = R_ES;
diff --git a/usr.bin/telnet/README b/usr.bin/telnet/README
index b23396efb536..5bec40d8848a 100644
--- a/usr.bin/telnet/README
+++ b/usr.bin/telnet/README
@@ -277,7 +277,7 @@ Februrary 22, 1991:
 	source route code is automatically enabled.
 
 	The NO_GETTYTAB #define has been removed; there
-	is a compatability routine that can be built into
+	is a compatibility routine that can be built into
 	libtelnet to achive the same results.
 
 	The server, telnetd, has been switched to use getopt()
diff --git a/usr.bin/tsort/tsort.c b/usr.bin/tsort/tsort.c
index 2f73a80d1fe9..746ea4f3f888 100644
--- a/usr.bin/tsort/tsort.c
+++ b/usr.bin/tsort/tsort.c
@@ -67,7 +67,7 @@ static char sccsid[] = "@(#)tsort.c	8.3 (Berkeley) 5/4/95";
  *     tsort [-dlq] [inputfile]
  *  If no input file is specified, standard input is read.
  *
- *  Should be compatable with AT&T tsort HOWEVER the output is not identical
+ *  Should be compatible with AT&T tsort HOWEVER the output is not identical
  *  (i.e. for most graphs there is more than one sorted order, and this tsort
  *  usually generates a different one then the AT&T tsort).  Also, cycle
  *  reporting seems to be more accurate in this version (the AT&T tsort
diff --git a/usr.sbin/pppd/options.c b/usr.sbin/pppd/options.c
index 0676e3c72a4e..2b70bc0e8ccd 100644
--- a/usr.sbin/pppd/options.c
+++ b/usr.sbin/pppd/options.c
@@ -2234,7 +2234,7 @@ setdeflate(argv)
     } else
 	ccp_allowoptions[0].deflate = 0;
 
-    /* XXX copy over settings for switch compatability */
+    /* XXX copy over settings for switch compatibility */
     ccp_wantoptions[0].baddeflate = ccp_wantoptions[0].deflate;
     ccp_wantoptions[0].baddeflate_size = ccp_wantoptions[0].deflate_size;
     ccp_allowoptions[0].baddeflate = ccp_allowoptions[0].deflate;
diff --git a/usr.sbin/ypbind/yp_ping.c b/usr.sbin/ypbind/yp_ping.c
index a88d8ff1c15d..558843f0c7fc 100644
--- a/usr.sbin/ypbind/yp_ping.c
+++ b/usr.sbin/ypbind/yp_ping.c
@@ -98,7 +98,7 @@ static const char rcsid[] =
 
 #ifndef timeradd
 #ifndef _KERNEL		/* use timevaladd/timevalsub in kernel */
-/* NetBSD/OpenBSD compatable interfaces */
+/* NetBSD/OpenBSD compatible interfaces */
 #define timeradd(tvp, uvp, vvp)						\
 	do {								\
 		(vvp)->tv_sec = (tvp)->tv_sec + (uvp)->tv_sec;		\