Webster's Revised Unabridged Dictionary · 1913

Saponify

Saponify , transitive verb

[Latin sapo, -onis, soap + -fy: compare French saponifier.]

(Chemistry) To convert into soap, as tallow or any fat; hence (Chemistry), to subject to any similar process, as that which ethereal salts undergo in decomposition; as, to saponify ethyl acetate.