photo-

1.
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
< Greek, combining form of phôs (genitive phōtós)
British Dictionary definitions for photo-

photo-

combining form
1.
of, relating to, or produced by light: photosynthesis
2.
indicating a photographic process: photolithography
Word Origin
from Greek phōs, phōt- light
Word Origin and History for photo-

word-forming element meaning "light" or "photographic" or "photoelectric," from Greek photo-, comb. form of phos (genitive photos) "light," from PIE root *bha- "to shine" (see phantasm).

photo- in Medicine

photo- or phot-
pref.

  1. Light; radiant energy: photosynthesis.

  2. Photographic: photofluorography.

photo- in Science
photo-  
A prefix that means "light," as in photoreceptor.