memo I. \ˈme(ˌ)mō sometimes ˈmē(-\noun (-s) Etymology: by shortening : memorandum II. transitive verb (-ed/ing/-s) 1.: to make a memorandum of or communicate in a memorandum < memoed what she'd have to do — Bernard Malamud > 2.: to send a memorandum to < we'll memo you in the morning — A.C.Spectorsky >