reducer

Estimated CEFR level: C2 — Proficiency

Estimated from word frequency; not an official CEFR classification.

Definition

noun a substance capable of bringing about the reduction of another substance as it itself is oxidized; used in photography to lessen the density of a negative or print by oxidizing some of the loose silver
noun pipefitting that joins two pipes of different diameter

From reduce + -er.

“In this, and a much worse plight than it is fit to trouble your excellent ears withal, did the king Euarchus find his estate when he took upon him the regiment, which, by reason of the long stream of abuse, he was forced to establish by some even extreme severity, not so much for the very faults themselves, which he rather sought to prevent than to punish, as for the faulty ones, who, strong even in their faults, scorned his youth, and could not learn to digest that the man which they so long had used to mask their own appetites, should now be the reducer of them into order. — The Countess of Pembroke's Arcadia, Philip Sidney

reducing agent, reductant

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