Fluorescein

/ˌflʊˈrɛsiːn/ noun

Definition

A bright green chemical dye that fluoresces under ultraviolet light, commonly used in medical tests and eye examinations.

Etymology

Derived from 'fluoresce' plus the chemical suffix '-in', indicating a chemical compound. It was first synthesized in 1871 from coal tar derivatives.

Kelly Says

Fluorescein is the exact dye optometrists use when they check if your eyes are healthy—they put it in drops and shine a special blue light to see the surface of your eye perfectly. It's also used by search and rescue teams to track water flow!

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