Noah Webster's Dictionary 1. (n.) A substance that can neutralize a base and is sour, sharp, or biting to the taste. 2. (a.) of or pertaining to an acid; as, acid reaction. 3. (n.) A sour substance. 4. (n.) One of a class of compounds, generally but not always distinguished by their sour taste, solubility in water, and reddening of vegetable blue or violet colors. They are also characterized by the power of destroying the distinctive properties of alkalis or bases, combining with them to form salts, at the same time losing their own peculiar properties. They all contain hydrogen, united with a more negative element or radical, either alone, or more generally with oxygen, and take their names from this negative element or radical. Those which contain no oxygen are sometimes called hydracids in distinction from the others which are called oxygen acids or oxacids.

Multi-Version Concordance Acid (2 Occurrences) Proverbs 10:26 Like acid drink to the teeth and as smoke to the eyes, so is the hater of work to those who send him. (BBE) Proverbs 25:20 Like one who takes off clothing in cold weather and like acid on a wound, is he who makes melody to a sad heart. (BBE)