shoot up verb 4shoot-up noun 1forms 4 verb4 •(figurative) To grow taller or larger rapidly.Our operating costs have shot up due to the fuel shortage.He was a small child, but shot up when he reached his teenage years. •To inject (a drug) intravenously.This place is always full of smackheads shooting up. •To fire many bullets or shells at.The terrorists decided to shoot up a convenience store. •To use up (ammunition) by shooting.Most of our ammunition has now been shot up. shoot-up noun1 •(informal) A shooting; a fight with firearms.We haven't had that kind of a shoot-up for more than two years! — 2008 formsshot up · shooting up · shoots up · shoot-ups