Lewis & Short

1. lībrārĭus, a, um, adj. [libra].

  1. I. Of or containing a pound, of a pound weight (post-Aug.): frusta, Col. 12, 53, 4: as, Gell. 20, 1, 31.
  2. II. Subst.
    1. A. lībrārĭus, ii, m., a weight, the sixteenth part of a modius, = sextarius: sextarius aequus aequo cum librario siet, sexdecimque librarii in modio sient, Plebisc. ap. Paul. ex Fest. p. 246 Müll.
    2. B. lībrārĭa, ae, f., she that weighed out the wool to the female slaves, a forewoman, head-spinner, called also lanipendia, Juv. 6, 475 (by others referred to 2. librarius); Inscr. Orell. 4212.