adulterate (v.)

"debase by mixing with foreign or inferior material, make corrupt," 1530s, back-formation from adulteration, or else from Latin adulteratus, past participle of adulterare "to falsify, corrupt," also "to commit adultery." Earlier verb was adulter (late 14c. in the sense "make impure"), directly from the Latin verb, but this English verb also carried the sense "commit adultery." Related: Adulterated; adulterating.

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Definitions of adulterate from WordNet
adulterate (v.)
corrupt, debase, or make impure by adding a foreign or inferior substance; often by replacing valuable ingredients with inferior ones;
adulterate liquor
Synonyms: load / stretch / dilute / debase
adulterate (adj.)
mixed with impurities;
Synonyms: adulterated / debased