diff

Noun

• Abbreviation of difference
• Any program which compares two files or sets of files and outputs a description of the differences between them.
• The output of a diff program. A diff file.
• Abbreviation of differential: differential of types of white blood cell in a complete blood count.
• A difficult route.

Verb

• To run a diff program on (files or items) so as to produce a description of the differences between them, as for a patch file.
• To compare two files or other objects, manually or otherwise.

Proper Noun

• A program, historically part of the Unix operating system, which compares two files or sets of files and outputs a description of the differences between them.