the.com/adulteration

means The act of debasing a product's purity or quality by mixing in inferior, cheaper, or foreign substances, usually while still selling it under the original name.

from From Latin 'adulterare,' meaning 'to corrupt' or 'to defile' — the same root that gives us 'adultery.' Both words share the sense of something pure being mixed with what doesn't belong, of a bond or standard broken by an outside intrusion. The Latin itself likely traces to 'ad-' (toward) plus 'alter' (other) — literally a turning toward 'the other,' a corrupting foreign element sneaking into what should be whole and unmixed.