Of a substance: to initiate (a chemical change) by absorbing light energy and transferring it to a reactant.
To make photosensitive.
Today’s NYT Connections Answers May 1, #325 - Daily Updates & Hints
Today’s Wordle Answer May 1 #1047- NYT Wordle Hints & Updates
NYT Mini Crossword Answers Today - The Mini for May 1 Solved
NYT Strands Today - Hints, Spangram & Answers for May 1