Main Entry: flu·o·res·ce·in

Pronunciation: \-ˈes-ē-ən\

Function: noun

: a yellow or red crystalline dye C₂₀H₁₂O₅ with a bright yellow-green fluorescence in alkaline solution that is used as the sodium salt as an aid in diagnosis (as of lesions and foreign bodies in the cornea or of brain tumors)