jimpy adjective 2noun 2forms 3 adjective2 •Neat, jimp.[…]though more than a hundred folk sitting in his company had beheld him dauting her with his arm round her jimpy waist, not five minutes before. — 1911 •Of, pertaining to, carrying or affected by the mutation. noun2 •(slang) A general-purpose machine gun (GPMG).Before they had come to a standstill, the protective cover had come off the powerful twin GPMG ‘jimpies’ mounted in the rear compartment by the laconic Australian, Corporal Kangers Webster. — 1985 •A sex-linked mutation in mice that causes severe hypomyelination in males.When cerebellar tissues from normal and Jimpy are grown on the same slide in a common medium, no mutual effects can be observed: the Jimpy does not myelinate, and the normal does not stop myelination. — 1973 formsjimpies · more jimpy · most jimpy