What does Suffix mean (in linux)?

From: Roxanne Kedge (missroxanner_at_excite.com)
Date: 11/27/03

Date: Thu, 27 Nov 2003 05:19:54 -0500

if you do man mv (you get following)

-S, --suffix=SUFFIX override the usual backup suffix

i typed "suffix" in www.dictionary.com got following...

An affix (singular of suffix?) added to the end of a word or stem, serving
to form a new word or functioning as an inflectional ending, such as -ness
in gentleness, -ing in walking, or -s in sits.

how do you override the backup suffix? (whatever suffix is?)