Definition of acid:

• Of or pertaining to an acid; as, acid reaction.
• A solution with a ph below 7. It has a sour taste, releases hydorxyl, and makes litmus papers red. Strong acids are corrosive and weak ones are practically harmless. AKA mineral, inorganic, natural, and organic acids.
• a powerful hallucinogenic drug
• A sour substance.
• A sour substance, usually liquid; that which combines with a base to form a salt.
• A sour substance: ( chem.) one of a class of substances, usually sour, which turn vegetable dyes to red, and combine with alkalies, metallic oxides, etc., to form salts.
• A sour substance; that which unites with a base to form a salt.
• Any sour substance.
• A compound of hydrogen capable of uniting with a a bse to form a salt.
• A sour substance; a substance capable of uniting with salifiable bases and forming salts.
• Something which causes sourness to the taste.
• any of various water- soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
• containing acid; " an acid taste"
• Sour, sharp, or biting to the taste; tart; having the taste of vinegar: as, acid fruits or liquors. Also fig.: Sour- tempered.
• 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 alkalies 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.
• Sour, and sharp or biting to the taste, as vinegar.
• A sour substance; very pungent; reddens litmus paper.
• Sharp: sour.
• Sharp to the taste, as vinegar; sour; of or like an acid.
• Sour and sharp to the taste.
• Sour; sharp; biting to the taste.

Usage examples for acid

1. She's only an acid- drop, and you can't size her up, just as an ordinary girl.  The Mandarin's Fan by Fergus Hume

2. If he lives for himself alone and for what, in the first glad bursts of unattachment he imagines to be pleasure, a day will come when the acid of self- contempt begins to corrode him.  We Three by Gouverneur Morris

3. 2. The acidity is expressed in percentage amounts of what acid?  Human Foods and Their Nutritive Value by Harry Snyder

4. Then it seemed best to use the acid.  The Crime of the French Café and Other Stories by Nicholas Carter