Lewis & Short

2. Nŭmĕrĭus, ii, m., abbrev. N., a Roman praenomen: qui celeriter erant nati, fere Numerios praenominabant, Varr. ap. Non. 352, 29. Concerning the introduction of this praenomen into the Fabian gens, v. Paul. ex Fest. p. 170 Müll. So, Numerius (abbrev. N.) Fabius Buteo, Liv. 41, 28: N. Fabius Vibulanus, a consul, id. 4, 43: Numerius, Numestius, Cic. Att. 2, 22, 7; 24, 1, 5.
(Fem. Numeria was not in use, Varr. L. L. 9, § 55 Müll.)