diff --git a/contrib/pg_trgm/trgm_regexp.c b/contrib/pg_trgm/trgm_regexp.c
index 1330b615b8..21e8a9f343 100644
--- a/contrib/pg_trgm/trgm_regexp.c
+++ b/contrib/pg_trgm/trgm_regexp.c
@@ -73,7 +73,7 @@
  * (two prefix colors plus a state number from the original NFA) an
  * "enter key".
  *
- * Each arc of the expanded graph is labelled with a trigram that must be
+ * Each arc of the expanded graph is labeled with a trigram that must be
  * present in the string to match.  We can construct this from an out-arc of
  * the underlying NFA state by combining the expanded state's prefix with the
  * color label of the underlying out-arc, if neither prefix position is
@@ -123,7 +123,7 @@
  * false positives that we would have to traverse a large fraction of the
  * index, the graph is simplified further in a lossy fashion by removing
  * color trigrams. When a color trigram is removed, the states connected by
- * any arcs labelled with that trigram are merged.
+ * any arcs labeled with that trigram are merged.
  *
  * Trigrams do not all have equivalent value for searching: some of them are
  * more frequent and some of them are less frequent. Ideally, we would like
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index efd7201d61..9092b4b309 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -4238,7 +4238,7 @@ ExplainOpenGroup(const char *objtype, const char *labelname,
 			/*
 			 * In YAML format, the grouping stack is an integer list.  0 means
 			 * we've emitted nothing at this grouping level AND this grouping
-			 * level is unlabelled and must be marked with "- ".  See
+			 * level is unlabeled and must be marked with "- ".  See
 			 * ExplainYAMLLineStarting().
 			 */
 			ExplainYAMLLineStarting(es);
@@ -4601,7 +4601,7 @@ ExplainJSONLineEnding(ExplainState *es)
  *
  * YAML lines are ordinarily indented by two spaces per indentation level.
  * The text emitted for each property begins just prior to the preceding
- * line-break, except for the first property in an unlabelled group, for which
+ * line-break, except for the first property in an unlabeled group, for which
  * it begins immediately after the "- " that introduces the group.  The first
  * property of the group appears on the same line as the opening "- ".
  */
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 357850624c..5ac7fed6a4 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -367,7 +367,7 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 	 * parallel-restricted, and in either case it should be OK to impose
 	 * parallel-mode restrictions.  If that ends up breaking something, then
 	 * either some function the user included in the query is incorrectly
-	 * labelled as parallel-safe or parallel-restricted when in reality it's
+	 * labeled as parallel-safe or parallel-restricted when in reality it's
 	 * parallel-unsafe, or else the query planner itself has a bug.
 	 */
 	glob->parallelModeNeeded = glob->parallelModeOK &&
diff --git a/src/pl/plpgsql/src/expected/plpgsql_control.out b/src/pl/plpgsql/src/expected/plpgsql_control.out
index 73b23a35e5..fbfc939eae 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_control.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_control.out
@@ -349,7 +349,7 @@ begin
   end loop flbl1;
 end;
 $$ language plpgsql;
-ERROR:  end label "flbl1" specified for unlabelled block
+ERROR:  end label "flbl1" specified for unlabeled block
 LINE 5:   end loop flbl1;
                    ^
 -- should fail: end label does not match start label
@@ -374,7 +374,7 @@ begin
   end loop outer_label;
 end;
 $$ language plpgsql;
-ERROR:  end label "outer_label" specified for unlabelled block
+ERROR:  end label "outer_label" specified for unlabeled block
 LINE 6:   end loop outer_label;
                    ^
 -- unlabeled exit matches no blocks
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 9a87cd70f1..9a0fa14ec8 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -212,21 +212,21 @@ static HTAB *shared_cast_hash = NULL;
 	{ \
 		if (estate->exitlabel == NULL) \
 		{ \
-			/* unlabelled EXIT terminates this loop */ \
+			/* unlabeled EXIT terminates this loop */ \
 			rc = PLPGSQL_RC_OK; \
 			exit_action; \
 		} \
 		else if ((looplabel) != NULL && \
 				 strcmp(looplabel, estate->exitlabel) == 0) \
 		{ \
-			/* labelled EXIT matching this loop, so terminate loop */ \
+			/* labeled EXIT matching this loop, so terminate loop */ \
 			estate->exitlabel = NULL; \
 			rc = PLPGSQL_RC_OK; \
 			exit_action; \
 		} \
 		else \
 		{ \
-			/* non-matching labelled EXIT, propagate RC_EXIT out */ \
+			/* non-matching labeled EXIT, propagate RC_EXIT out */ \
 			exit_action; \
 		} \
 	} \
@@ -234,19 +234,19 @@ static HTAB *shared_cast_hash = NULL;
 	{ \
 		if (estate->exitlabel == NULL) \
 		{ \
-			/* unlabelled CONTINUE matches this loop, so continue in loop */ \
+			/* unlabeled CONTINUE matches this loop, so continue in loop */ \
 			rc = PLPGSQL_RC_OK; \
 		} \
 		else if ((looplabel) != NULL && \
 				 strcmp(looplabel, estate->exitlabel) == 0) \
 		{ \
-			/* labelled CONTINUE matching this loop, so continue in loop */ \
+			/* labeled CONTINUE matching this loop, so continue in loop */ \
 			estate->exitlabel = NULL; \
 			rc = PLPGSQL_RC_OK; \
 		} \
 		else \
 		{ \
-			/* non-matching labelled CONTINUE, propagate RC_CONTINUE out */ \
+			/* non-matching labeled CONTINUE, propagate RC_CONTINUE out */ \
 			exit_action; \
 		} \
 	} \
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index 6778d0e771..5a7e1a4444 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -1725,7 +1725,7 @@ stmt_exit		: exit_type opt_label opt_exitcond
 						{
 							/*
 							 * No label, so make sure there is some loop (an
-							 * unlabelled EXIT does not match a block, so this
+							 * unlabeled EXIT does not match a block, so this
 							 * is the same test for both EXIT and CONTINUE)
 							 */
 							if (plpgsql_ns_find_nearest_loop(plpgsql_ns_top()) == NULL)
@@ -3749,7 +3749,7 @@ check_labels(const char *start_label, const char *end_label, int end_location)
 		if (!start_label)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
-					 errmsg("end label \"%s\" specified for unlabelled block",
+					 errmsg("end label \"%s\" specified for unlabeled block",
 							end_label),
 					 parser_errposition(end_location)));
 
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 1af2595e34..0c3d30fb13 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -833,7 +833,7 @@ typedef struct PLpgSQL_stmt_exit
 	int			lineno;
 	unsigned int stmtid;
 	bool		is_exit;		/* Is this an exit or a continue? */
-	char	   *label;			/* NULL if it's an unlabelled EXIT/CONTINUE */
+	char	   *label;			/* NULL if it's an unlabeled EXIT/CONTINUE */
 	PLpgSQL_expr *cond;
 } PLpgSQL_stmt_exit;