Lewis & Short

unguĭcŭlus, i, m. dim. [unguis], a finger-nail: integritas unguiculorum omnium, Cic. Fin. 5, 27, 80; Plaut. Ep. 5, 1, 17; Sen. Q. N. 6, 2, 5.
Prov.: a teneris unguiculis, a transl. of the Gr. ἐξ ἁπαλῶν ὀνύχων, from early infancy, from childhood, Cic. Fam. 1, 6, 2 (for which: de tenero ungui, Hor. C. 3, 6, 24): ex unguiculis (= ἐξ ὀνύχων), from the very finger-tips, i. e. through and through, Plaut. Stich. 5, 5, 20; App. M. 10, p. 249, 11.