математика; сокращение от difference разность
noun slang difference
/dif/ 1. A change listing, especially giving differences between (and additions to) different versions of a piece of source code or documentation (the term is often used in the plural "diffs"). "Send me your diffs for the Jargon File!" Compare vdiff. 2. Specifically, such a listing produced by the diff Unix command, especially when used as input to the patch utility (which actually performs the modifications). This is a common method of distributing patches and source updates. 3. To compare (whether or not by use of automated tools on machine-readable files). See also vdiff, mod.