penta-

1. a combining form occurring in loanwords from Greek, meaning “five” (Pentateuch); on this model, used in the formation of compound words (pentavalent).

combining form

1. fivepentagon; pentameter; pentaprism

word-forming element meaning “five, containing five,” from Greek penta- (before a vowel pent-), comb. form of pente “five,” related to Aeolian pempte (see five), with -a- by analogy of hepta-, ennea-, deka-. pref.

1. Five:pentameter.
2. Containing five atoms, molecules, or groups:pentose.