Lewis & Short

palmārĭus, a, um, adj. [1. palma],

  1. I. of or belonging to palms: Insula Palmaria, the Isle of Palms in the Tyrrhenian Sea, now Palmarola, Varr. R. R. 3, 5, 7; Plin. 3, 6, 12, § 81.
  2. II. Transf., subst.: palmārĭ-um, ii, n.
    1. * A. That which deserves the prize, a masterpiece: id vero est, quod ego mihi puto palmarium, Ter. Eun. 5, 4, 8.
    2. B. The fee of a successful advocate, Dig. 50, 13, 1, § 12; cf. palmarium, ἀξιόνικον, Gloss. Philox.