An audio or video digital sample cut so that it plays continuously without jarring. (Nobody uses analogue tape or film anymore, unless they're into masochism)
Often: "drum loop" ~ a pattern of drum hits which, when combined with a bassline, make a groove. These can be stored as an audio file or MIDI information.
Mate, that loop's fucked up. It needs to be a coupla milliseconds shorter to fit into the groove. Or make the bassline longer to fit it.
"The Loop" is the localname for Chicago's downtown area, so named because of the way the city's elevated trains (or el) loops around the area. Also used with directions, such as "North Loop," "South Loop," or "West Loop." There is, however, no "East Loop" because that would put you in Lake Michigan.