[foh-tuh-juh n, -jen]
  1. a light oil obtained by the distillation of bituminous shale, coal, or peat: once commercially produced chiefly as an illuminant and as a solvent.
  2. Biology. a photogenic organ, organism, or substance.

Origin of photogen

First recorded in 1855–60; photo- + -gen Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for photogen

Historical Examples of photogen