Fat \Fat\, v. t. [imp. & p. p. {Fatted}; p. pr. & vb. n. {atting}.] [OE. fatten, AS. f[=ae]ttian. See {Fat}, a., and cf. {Fatten}.] To make fat; to fatten; to make plump and fleshy with abundant food; as, to fat fowls or sheep. We fat all creatures else to fat us. --Shak.