Closes #18927: Lock.acquire only accepts -1 or positive values for timeout.
diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst
index 5eb0069..7c326d1 100644
--- a/Doc/library/threading.rst
+++ b/Doc/library/threading.rst
@@ -378,7 +378,7 @@
When invoked with the floating-point *timeout* argument set to a positive
value, block for at most the number of seconds specified by *timeout*
- and as long as the lock cannot be acquired. A negative *timeout* argument
+ and as long as the lock cannot be acquired. A *timeout* argument of ``-1``
specifies an unbounded wait. It is forbidden to specify a *timeout*
when *blocking* is false.