from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Chemical decomposition induced by light or other radiant energy.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any chemical reaction in which a compound is decomposed after absorbing a photon
from The Century Dictionary and Cyclopedia
- n. In botany, the movements of protoplasm under the influence of light: distinguished as apostrophe and epistrophe.
From Ancient Greek φωτ- (phōt-), root of φῶς (phōs, "light") + λύσις (lusis, "decomposition"). (Wiktionary)