To make something impure by adding an inferior substance; to make something lower in quality by mixing it with something else.
From Latin adulterare, from ad- (to) plus alterare (to change or alter), literally meaning 'to make other' or 'to change.' Used since medieval times for mixing substandard materials into goods.
Adulterate originally described cheating in commerce—mixing cheap grain into expensive grain—which is why it now describes any kind of deception that reduces quality, from food to morals to language.
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