Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sŏnor, ōris, m. [sono], a noise, sound, din (poet. and in post-Aug. prose for sonitus and sonus); sing., Lucr. 1, 644; 4, 567; 4, 570; Verg. G. 3, 199; id. A. 7, 462; Tac. A. 1, 65; 4, 48; App. M. 11, p. 258 fin.
Plur., Lucr. 5, 334; 6, 1185; Verg. A. 9, 651; Val. Fl. 5, 306; Tac. A. 14, 36; App. Dogm. Plat. 1, p. 9, 28; id. Flor. 3, p. 357, 4.
sŏnōrus, a, um (collat. form sŏnōris, e, Diom. 497 and 498), adj. [sonor], noisy, loud, sounding, resounding, sonorous (poet. and in post-Aug. prose for the class. sonans): cithara, Tib. 3, 4, 69: aes, Claud. IV. Cons. Hon. 149: arcus, id. in Ruf. 2, 80: tempestates sonoras, Verg. A. 1, 53: tonitru, Claud. Laud. Stil. 2, 26: pelage, Lucr. 5, 35 Lachm.: flumina, Verg. A. 12, 139: nemus, Stat. Th. 4, 34: Phocis (on account of the Delphic oracle), id. ib. 11, 281: insula fluctibus, Claud. B. Gild. 512: versus qui crepitant pronuntiatione fragosā et exsultantem informant dictionem, ut (Verg. A. 9, 503): at tuba terribilem, etc., Diom. p. 498 P.
* Adv.: sŏnōrē, loudly: oscitavit (with clare), Gell. 4, 20, 8.