Acid

How to spell acid

4 letters · 2 syllables

How to pronounce acid

Say the part in capitals loudest.

What does acid mean?

1. nounA chemical substance that neutralises alkalis, turns litmus red, and is often corrosive or sour.
2. adjectiveHaving a sour, sharp taste, or describing a bitingly critical tone.

Acid in a sentence

• noun

  The technician poured the acid carefully into a labelled flask.

• adjective

  Her acid reply silenced everyone at the meeting.

• noun

  Battery acid can burn skin and damage clothing on contact.

• adjective

  The wine had an unpleasantly acid aftertaste.

Where does acid come from?

Language of origin: Latin

The word comes from the Latin acidus, meaning 'sour' or 'sharp to the taste', which was built on the verb acere, 'to be sour'. That same Latin stem, with its core idea of a biting, sharp edge, also gave English words like 'acrid', 'acute', and 'vinegar' (through acetum, 'sour wine'). English adopted acid in the early 1600s, first as an adjective describing a sour taste and soon afterwards as a noun for the class of sour, corrosive chemical substances that chemists were beginning to study. Over time the figurative sense developed too, so a sharp, cutting remark could be called acid. The spelling is mercifully regular, staying close to the original Latin, which is why the simple -id ending rarely trips writers up.

How the word is built

• acid (from Latin acidus: sour, sharp)
• (no affixes; the whole word descends from a single Latin adjective)