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

Origin of penta-

< Greek pent-, penta-, comb. forms representing pénte five Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for penta-


combining form

fivepentagon; pentameter; pentaprism

Word Origin for penta-

from Greek pente five
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for penta-


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-.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for penta-



Containing five atoms, molecules, or groups:pentose.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.