Insufficient synonyms such as in short supply, at a premium, and deficient. Insufficient is an adjective, and its antonyms are sufficient and adequate. Additionally, here are 28 synonyms, related words, and verbs for insufficient.
at a premium, deficient, exiguous, in short supply, inadequate, incomplete, lacking, limited, meagre, measly, not enough, paltry, pathetic, piddling, poor, restricted, scant, scanty, scarce, short, sketchy, skimpy, sparse, too few, too little, too small, and wanting.