palmus — Lewis & Short
palmus, i, m.1. palma,
I the palm of the hand.
I Lit.:
manūs palmum,Vitr. 2, 3:
Graeci antiqui doron palmum vocabant: et ideo dora munera, quia manu darentur,Plin. 35, 14, 49, § 171.—
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.