Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
fustis, is (abl. fusti, Plaut. As. 2, 4, 21; id. Capt. 4, 2, 116; Val. Max. 6, 3, 9; Tac. A. 14, 8 al., or fuste, Hor. S. 1, 3, 134; 1, 5, 23; 2, 3, 112; Juv. 9, 98; Val. Max. 8, 1, 1; Dig. 9, 2, 7, § 1 al.), m. [through the forms fonstis, fond-tis, from root of -fendo, found in offendo, defendo, etc.; cf.: mani-festus, in-festus, con-festim, festino; Gr. θείνειν, to strike, Curt. Gr. Etym. p. 255; Corss. Ausspr. 2, 190], a knobbed stick, a cudgel, staff, club (syn.: sceptrum, scipio, ferula, baculum): tamquam si claudus sim, cum fusti est ambulandum, Plaut. As. 2, 4, 21; Varr. L. L. 5, § 137 Müll.: severae Matris ad arbitrium recisos Portare fustes, Hor. C. 3, 6, 41; for threshing out grain: ipsae spicae melius fustibus cuduntur, Col. 2, 20, 4.
Esp. for cudgelling: auferere, non abibis, si ego fustem sumpsero, Plaut. Am. 1, 1, 202: male mulctati clavis ac fustibus, Cic. Verr. 2, 4, 43, § 94: non opus est verbis, sed fustibus, id. Pis. 30, 73: si filius meus fustem mihi impingere volet? Cael. ap. Cic. Fam. 8, 8, 9: quos tu nisi fuste coërces, Hor. S. 1, 3, 134: mulae caput fuste dolare, id. ib. 1, 5, 22: fuste aperire caput, Juv. 9, 98: injuria committitur cum quis fuste percussus erit, Gai Inst. 3, 220: fustium admonitio, Dig. 48, 19, 7.
And for beating to death, as a milit. punishment (v. fustuarium): sorte ductos fusti necat, Sall. H. Fragm. 4, 5 Dietsch: primipili centurionem ob turpem ex acie fugam fusti percussit, Vell. 2, 78 fin.; Tac. A. 3, 21; Front. S. 4, 1, 34 Oud.; Auct. B. Hisp. 27 fin.; Paul. Sent. 5, 18, 1; 5, 21, 1.
Hence: formidine fustis (i. e. to be beaten to death) ad bene dicendum redacti, Hor. Ep. 2, 1, 154.