This week's theme: short words. heft (heft) noun 1. Weight; heaviness. 2. Importance. verb tr. 1. To test the weight of something by lifting. 2. To heave or hoist. [After heave, on the pattern of cleave/cleft, leave/left, thieve/theft, weave/weft, etc. From Middle English heven (to lift, take).]... Sign in to see full entry.