Acid, sour, and bitter agree in being contrasted with sweet, but the two former are sharply distinguished from the latter. Acid or sour is the taste of vinegar or lemon-juice; bitter that of quassia, quinine, or strychnine.

J. C. Fernald, English Synonyms and Antonyms (1914)

Example sentences

sour Those grapes look sweet, but in fact they're sour.
caustic Our English teacher likes to make caustic comments.
acrid There's an acrid smell here. Is something burning?
sulphurous Medicinal waters generally have a sulphurous taste.

Popularity over time

Word	1850 → 2019	Trend
acid		falling
sour		rising
caustic		falling
acrid		rising
sulphurous		steady

Use in printed books, per decade from 1850 to 2019.

By length

4 letters: sour², tart¹
5 letters: sharp¹, acrid², acerb
6 letters: bitter², acidic³
7 letters: caustic², acerbic³, acetous
8 letters: virulent³
9 letters: vitriolic⁴, sulfurous, acidulous, acidulent
10 letters: blistering³, sulphurous

The small number after each word is its number of syllables (sour² = 2 syllables).

In other languages

Français: revêche