Lewis & Short

palmus, i, m. [1. palma], the palm of the hand.

  1. I. Lit.: manūs palmum, Vitr. 2, 3: Graeci antiqui doron palmum vocabant: et ideo dora munera, quia manu darentur, Plin. 35, 14, 49, § 171.
  2. II. Transf., as a measure of length, a span, or twelve digits, Varr. R. R. 3, 7: amomum frutex myrtuosus, palmi altitudine, Plin. 12, 13, 28, § 48: minor, a smaller measure, a palm, or four digits, acc. to Vitr. 3, 1, 5.