typo

Doc/lib/libsys.tex

@@ -21,7 +21,7 @@ It is always available.
 
 \begin{datadesc}{byteorder}
   An indicator of the native byte order.  This will have the value
-  \code{'big'} on big-endian (most-signigicant byte first) platforms,
+  \code{'big'} on big-endian (most-significant byte first) platforms,
   and \code{'little'} on little-endian (least-significant byte first)
   platforms.
   \versionadded{2.0}