jim noun 1verb 1forms 4phrases 1 noun1 •(Australia, informal) A one-pound banknote.He was tearin' ratty t' raise another jim. — 1906 verb1 •(informal) To jimmy (something); to mess up or mess with (something). formsjimmed · jimming · jims · Jims Phrases with jim jim upTo mess up, break down, gummy up or slow down (something).