Lewis & Short

farrĕus, a, um, adj. [far],

  1. I. made of spelt, or in gen. of corn or grain: far. vel triticeus panis, Col. 7, 12, 10: spicum, an ear of corn, Paul. ex Fest. p. 280, 9 Müll.
  2. II. Subst.: farrĕum, i, n. (sc. libum), a speltcake, Plin. 18, 3, 3, § 10.