--- a/docs/concepts.rst	Sat Apr 27 21:24:18 2019 -0400
+++ b/docs/concepts.rst	Sat Apr 27 21:27:54 2019 -0400
@@ -92,7 +92,7 @@
 think of the traditional parent/child DAG as the first derivative of
 your source code, and the obsolescence DAG as the second derivative.)
 
-Troubled changesets (orphan, bumped, divergent)
+Unstable changesets (orphan, bumped, divergent)
 -----------------------------------------------
 
 Evolving history can introduce problems that need to be solved. For
@@ -133,17 +133,17 @@
 public phase; only mutable changesets are divergent).
 
 The collective term for orphan, bumped, and divergent changeset is
-*troubled*::
+*unstable*::
 
-  troubled = orphan ∪ bumped ∪ divergent
+  unstable = orphan ∪ bumped ∪ divergent
 
-It is possible for a changeset to be in any of the troubled categories
+It is possible for a changeset to be in any of the unstable categories
 at the same time: it might be an orphan and divergent, or bumped and
 divergent, or whatever.
 
-  [diagram: Venn diagram of troubled changesets, showing overlap]
+  [diagram: Venn diagram of unstable changesets, showing overlap]
 
-The presence of troubled changesets indicates the need to run ``hg
+The presence of unstable changesets indicates the need to run ``hg
 evolve``.
 
 Hidden (and visible) changesets
@@ -192,7 +192,7 @@
   hidden = hideable ∖ ancestors((repo ∖ hideable) ∪ blockers)
 
 This will probably be clearer with a worked example. First, here's a
-repository with some obsolete changesets, some troubled changesets,
+repository with some obsolete changesets, some unstable changesets,
 one bookmark, a working copy, and some hidden changesets::
 
         x-x