Definition of phototoxicity in US English:

phototoxicity

noun

Biology Medicine
  • Toxic or adverse effects caused by the reaction of light with a photoactive compound present within the body, on the skin, or in the environment; non-allergic effects of this nature.

Origin

1940s. From photo- + toxicity. Compare earlier phototoxic.

Pronunciation

phototoxicity

/ˌfəʊtəʊtɒkˈsɪsɪti/