Misspellling: "occurance" --> "occurrence"
diff --git a/Doc/lib/libre.tex b/Doc/lib/libre.tex
index 7c7d177..b9f5f32 100644
--- a/Doc/lib/libre.tex
+++ b/Doc/lib/libre.tex
@@ -447,7 +447,7 @@
occurrences of \var{pattern} in \var{string} by the replacement
\var{repl}. If the pattern isn't found, \var{string} is returned
unchanged. \var{repl} can be a string or a function; if a function,
-it is called for every non-overlapping occurance of \var{pattern}.
+it is called for every non-overlapping occurrence of \var{pattern}.
The function takes a single match object argument, and returns the
replacement string. For example: