pēnĭcillum — Lewis & Short
pēnĭcillum, i, n., and pēnĭcillus, i, m.dim.peniculus, lit., a little tail; hence, acc. to diverse usage,
caudam antiqui penem vocabant, ex quo est propter similitudinem penicillus,Cic. Fam. 9, 22, 2; id. Or. 22, 74; Quint. 2, 21, 24:
setae e penicillis tectoriis,Plin. 28, 17, 71, § 235; Paul. Sent. 3, 6, 63.—
modo mihi date Britanniam, quam pingam coloribus tuis, penicillo meo,Cic. Q. Fr. 2, 15, 2.—