(1) Means “after,” as opposed to pre. In recording studio parlance, it is used to indicate that the signal has already had the designated effect added, such as post-equalization, post-effects, or post-fader. Also used as an abbreviation for post-production.

(2) Binding post. A connector, consisting of a threaded shaft and nut, used to terminate bare wire. Usually found on loudspeakers and occasionally amplifiers.

See pigtail.