The Collaborative International Dictionary of English v.0.48:

Photo \Pho"to\ (f[=o]"t[-o]), n.; pl. Photos (f[=o]"t[-o]z).
   A contraction of Photograph. [Colloq.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Photo- \Pho"to-\ (f[=o]"t[-o]-).
   A combining form from Gr. fw^s, fwto`s, light; as,
   photography, phototype, photometer.
   [1913 Webster]