noun, plural pho·tos.

Nearby words

  1. photic zone,
  2. photics,
  3. photinia,
  4. photism,
  5. photius,
  6. photo call,
  7. photo essay,
  8. photo finish,
  9. photo layout,
  10. photo op

Origin of photo

First recorded in 1855–60; shortened form of photograph


a combining form meaning “light” (photobiology); also used to represent “photographic” or “photograph” in the formation of compound words: photocopy.
Also especially before a vowel, phot-.

Origin of photo-

< Greek, combining form of phôs (genitive phōtós) Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for photo

British Dictionary definitions for photo


noun plural -tos


combining form

of, relating to, or produced by lightphotosynthesis
indicating a photographic processphotolithography

Word Origin for photo-

from Greek phōs, phōt- light

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 photo
Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for photo



Light; radiant energy:photosynthesis.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for photo


A prefix that means “light,” as in photoreceptor.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.