jam up verb 3jam-up adjective 1jam-up noun 1forms 4 verb3 •To cause (something) to become blocked or clogged; to clog up. •To become blocked or clogged.The traffic jammed up on the boulevard. •(figurative) To cause trouble; to stop or inhibit (someone, something). jam-up adjective1 •(dialect, US) Splendid; wonderful; upstanding.Pete's a real jam-up guy. jam-up noun1 •The situation where material becomes jammed in a machine, or some process similarly grinds to a halt.The rationale goes something like this: Increasing line speeds, complex packaging equipment, and ever-lighter-weight containers and packaging materials make jam-ups likely—usually many per day. — 2010 formsjammed up · jamming up · jams up · jam-ups
