Adulterate, v. t. [imp. & p. p. Adulterated; p. pr. & vb. n Adulterating.] — Webster enters it under “adulterate”
Etymology: [L. adulteratus, p. p. of adulterare, fr. adulter adulterer, prob. fr. ad + alter other, properly one who approaches another on account of unlawful love. Cf. Advoutry.]
1. To defile by adultery. [Obs.] Milton.
2. To corrupt, debase, or make impure by an admixture of a foreign or a baser substance; as, to adulterate food, drink, drugs, coin, etc. The present war has . . . adulterated our tongue with strange words. Spectator.
Syn. -- To corrupt; defile; debase; contaminate; vitiate; sophisticate.
2 other Webster entries under this spelling
Adulterate, v. i.
To commit adultery. [Obs.]
Adulterate, a.
1. Tainted with adultery.
2. Debased by the admixture of a foreign substance; adulterated; spurious. -- A*dul"ter*ate*ly, adv. -- A*dul"ter*ate*ness, n.
Shades of meaning
Fernald lists adulterated only as an antonym, under pure.
He lists it without comment; the entries above explain its neighbors.