Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
imberbis (inb-), e, adj. [in-barba; cf.: infamis, informis], without a beard, beardless (rare but class.): non convenire barbatum esse filium (Aesculapium), cum pater (Apollo) imberbis esset, Cic. N. D. 3, 34, 83; 1, 30, 83; id. Cat. 2, 10, 22: quae Imberbes didicere, Hor. Ep. 2, 1, 85.
In the form imberbus, a, um: androgyni, Lucil. ap. Non. 493, 27; and ap. Charis. p. 74; Cic. Dom. 14, 37; id. Agr. 1, Fragm. 3 (ap. Charis. p. 74): quod maximi sunt iidemque imberbi, Varr. ap. Non. 493, 30: imberbus juvenis, Hor. A. P. 161 Orell. N. cr.