diff --git a/contrib/check-code.py b/contrib/check-code.py
--- a/contrib/check-code.py
+++ b/contrib/check-code.py
@@ -177,6 +177,7 @@ pypats = [
      "always assign an opened file to a variable, and close it afterwards"),
     (r'[\s\(](open|file)\([^)]*\)\.',
      "always assign an opened file to a variable, and close it afterwards"),
+    (r'(?i)descendent', "the proper spelling is descendAnt"),
   ],
   # warnings
   [
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1456,7 +1456,7 @@ class localrepository(repo.repository):
 
     def changegroupsubset(self, bases, heads, source):
         """Compute a changegroup consisting of all the nodes that are
-        descendents of any of the bases and ancestors of any of the heads.
+        descendants of any of the bases and ancestors of any of the heads.
         Return a chunkbuffer object whose read() method will return
         successive changegroup chunks.
 
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -491,7 +491,7 @@ class revlog(object):
                 return nonodes
             lowestrev = min([self.rev(n) for n in roots])
         else:
-            roots = [nullid] # Everybody's a descendent of nullid
+            roots = [nullid] # Everybody's a descendant of nullid
             lowestrev = nullrev
         if (lowestrev == nullrev) and (heads is None):
             # We want _all_ the nodes!
@@ -528,7 +528,7 @@ class revlog(object):
                 r = self.rev(n)
                 if r >= lowestrev:
                     if n not in ancestors:
-                        # If we are possibly a descendent of one of the roots
+                        # If we are possibly a descendant of one of the roots
                         # and we haven't already been marked as an ancestor
                         ancestors.add(n) # Mark as ancestor
                         # Add non-nullid parents to list of nodes to tag.
@@ -562,41 +562,41 @@ class revlog(object):
                 lowestrev = nullrev
                 roots = [nullid]
         # Transform our roots list into a set.
-        descendents = set(roots)
+        descendants = set(roots)
         # Also, keep the original roots so we can filter out roots that aren't
         # 'real' roots (i.e. are descended from other roots).
-        roots = descendents.copy()
+        roots = descendants.copy()
         # Our topologically sorted list of output nodes.
         orderedout = []
         # Don't start at nullid since we don't want nullid in our output list,
         # and if nullid shows up in descedents, empty parents will look like
-        # they're descendents.
+        # they're descendants.
         for r in xrange(max(lowestrev, 0), highestrev + 1):
             n = self.node(r)
-            isdescendent = False
-            if lowestrev == nullrev:  # Everybody is a descendent of nullid
-                isdescendent = True
-            elif n in descendents:
-                # n is already a descendent
-                isdescendent = True
+            isdescendant = False
+            if lowestrev == nullrev:  # Everybody is a descendant of nullid
+                isdescendant = True
+            elif n in descendants:
+                # n is already a descendant
+                isdescendant = True
                 # This check only needs to be done here because all the roots
-                # will start being marked is descendents before the loop.
+                # will start being marked is descendants before the loop.
                 if n in roots:
                     # If n was a root, check if it's a 'real' root.
                     p = tuple(self.parents(n))
-                    # If any of its parents are descendents, it's not a root.
-                    if (p[0] in descendents) or (p[1] in descendents):
+                    # If any of its parents are descendants, it's not a root.
+                    if (p[0] in descendants) or (p[1] in descendants):
                         roots.remove(n)
             else:
                 p = tuple(self.parents(n))
-                # A node is a descendent if either of its parents are
-                # descendents.  (We seeded the dependents list with the roots
+                # A node is a descendant if either of its parents are
+                # descendants.  (We seeded the dependents list with the roots
                 # up there, remember?)
-                if (p[0] in descendents) or (p[1] in descendents):
-                    descendents.add(n)
-                    isdescendent = True
-            if isdescendent and ((ancestors is None) or (n in ancestors)):
-                # Only include nodes that are both descendents and ancestors.
+                if (p[0] in descendants) or (p[1] in descendants):
+                    descendants.add(n)
+                    isdescendant = True
+            if isdescendant and ((ancestors is None) or (n in ancestors)):
+                # Only include nodes that are both descendants and ancestors.
                 orderedout.append(n)
                 if (ancestors is not None) and (n in heads):
                     # We're trying to figure out which heads are reachable
diff --git a/mercurial/simplemerge.py b/mercurial/simplemerge.py
--- a/mercurial/simplemerge.py
+++ b/mercurial/simplemerge.py
@@ -211,7 +211,7 @@ class Merge3Text(object):
         Method is as follows:
 
         The two sequences align only on regions which match the base
-        and both descendents.  These are found by doing a two-way diff
+        and both descendants.  These are found by doing a two-way diff
         of each one against the base, and then finding the
         intersections between those regions.  These "sync regions"
         are by definition unchanged in both and easily dealt with.
@@ -315,7 +315,7 @@ class Merge3Text(object):
     mismatch_region = staticmethod(mismatch_region)
 
     def find_sync_regions(self):
-        """Return a list of sync regions, where both descendents match the base.
+        """Return a list of sync regions, where both descendants match the base.
 
         Generates a list of (base1, base2, a1, a2, b1, b2).  There is
         always a zero-length sync region at the end of all the files.