Entry 3 senses · 3 variants Webster, 1913 Fust /(fŭst)/ · IPA /fʌst/ n. n. v. i. 01 n. The shaft of a column, or trunk of a pilaster. 1. The shaft of a column, or trunk of a pilaster.(Arch.) 02 n. A strong, musty smell; mustiness. 1. A strong, musty smell; mustiness. 03 v. i. To become moldy; to smell ill. 1. To become moldy; to smell ill.[Obs.]