(1) (verb) To connect together, as the inputs and outputs of various modules, generally with patch cords.
(2) (noun) The configuration of hookups and settings that results from the process of patching, and by extension, the sound that such a configuration creates. Patch is most often used to denote a single sound or the contents of a memory location that contains parameter settings for the sound, even on an instrument that requires no physical patching. A synonym for sample or program.