From WordNet (r) 2.0 (August 2003) [wn]:
photo
n : a picture of a person or scene in the form of a print or
transparent slide; recorded by a camera on
light-sensitive material [syn: photograph, exposure,
pic]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Photo \Pho"to\ (f[=o]"t[-o]), n.; pl. Photos (f[=o]"t[-o]z).
A contraction of Photograph. [Colloq.]
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Photo- \Pho"to-\ (f[=o]"t[-o]-).
A combining form from Gr. fw^s, fwto`s, light; as,
photography, phototype, photometer.
[1913 Webster]