SENSITIZER
sensitizer, sensitiser
(noun) (chemistry) a substance other than a catalyst that facilitates the start of a catalytic reaction
Source: WordNet® 3.1
Etymology
Noun
sensitizer (plural sensitizers)
Any agent that sensitizes something.
Chemical sensitizer, a chemical that causes allergic reaction in normal tissue after exposure.
Explosive sensitizer, a chemical that promotes the rate of propagation of an explosive material.
Source: Wiktionary
Sen"si*ti`zer, n. (Photog.)
Definition: An agent that sensitizes.
The sensitizer should be poured on the middle of the sheet. Wilis &
Clements (The Platinotype).
Source: Webster’s Unabridged Dictionary 1913 Edition