adulterate

adulterate \uh-DUHL-tuh-rayt\, verb:

1. to add an inferior, impure, or improper substance to; lower the quality or purity of a food or other substance without greatly altering the appearance; corrupt
2. debased by adulteration; adulterated

It would seem as if some men considered it a sin ever to sell a pure article, if it be possible to adulterate it with something cheaper.
-- Adulterated Drugs, Drinks, and Diet, New York Times, October 23, 1949

Industrial plant directors bent upon fulfilling the Plan adulterate their products to increase quantity.
-- Lance Morrow, The Inscrutable Soviets, Time, May 9, 1972

The disciples also promised not to adulterate milk with water, or flour with powdered stone.
-- Atomic Vows, Time, May 14, 1946

by 1505, from Latin adulterationem, from adulteratus, pp. of adulterare "corrupt, debauch," from ad- "to" + Late Latin alterare "to alter"