Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
tintinnābŭlum, i, n. [tintinno], a bell, signal-bell, e. g. on a door to summon the attendant, on the necks of cattle, etc., Plaut. Trin. 4, 2, 162; id. Ps. 1, 3, 98; Suet. Aug. 91; Plin. 36, 13, 19, § 92; Juv. 6, 441; Mart. 14, 163 in lemm.; Paul. Nol. Carm. 18, 336.