acid
Meaning of acid: An acid is a compound that releases hydrogen ions in water, ranging from digestive gastric acid to laboratory and industrial chemicals.
Definition of acid
An acid is a chemical compound that releases hydrogen ions when dissolved in water and reacts with certain metals and bases to form salts. Acids are generally characterized by a sour taste when safe to taste, and many can turn specific indicator dyes a distinct color, properties historically used to identify them before modern laboratory methods existed.
The body produces certain acids as part of normal function, most notably gastric acid within the stomach, which helps break down food and provides an environment that supports digestion and helps limit the growth of ingested microorganisms. Other biological acids, such as lactic acid and uric acid, arise from the body's own metabolism.
Acid strength varies considerably, measured using the pH scale, and acids of very different strengths are encountered both inside the body and in everyday household and industrial products, ranging from mild acids found in food to strong acids used in manufacturing.
Used in a sentence
Laboratory testing measured the stomach's gastric acid production as part of the evaluation.
Good to know
The word acid describes a broad chemical category rather than a single substance, so an acid's effect on the body depends entirely on which specific acid is involved and in what concentration.
Word origin
Where “acid” comes from
Formed from Latin acidus, meaning sour, describing the taste characteristic of many acids.