Lewis & Short

Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.

hinnĭo, īre (perf. hinnisset, Val. Max. 7, 3, ext. 2), v. n., to neigh, whinny: ut si finias equum, genus est animal, species mortale, differentia irrationale (nam et homo mortale erat), proprium hinniens, Quint. 7, 3, 3; Lucr. 5, 1077; Quint. 1, 5 fin.: hinnientium dulcedines, i. e. of horses, Laev. ap. App. Mag. p. 294.
Poet., of the centaur Chiron, Sid. Carm. 14, 29.
Hence, * hinnĭenter, adv., with neighing: hinnibunde pro hinnienter, Non. 122, 13.