Dictionary.net

/dif/ 1. A change listing, especially giving differencesbetween (and additions to) different versions of a piece ofsource code or documentation (the term is often used in theplural "diffs"). "Send me your diffs for the Jargon File!"Compare vdiff.2. Specifically, such a listing produced by the diff Unixcommand, especially when used as input to the patch utility(which actually performs the modifications). This is a commonmethod of distributing patches and source updates.3. To compare (whether or not by use of automated tools onmachine-readable files).See also vdiff, mod.