acidulous

adjective

1. slightly sour.
2. sharp; caustic: his acidulous criticism of the book.
3. moderately acid or tart; subacid.

adjective

1. rather sour
2. sharp or sour in speech, manner, etc; acid

adj.

1769, “sub-acidic,” used figuratively for “sour-tempered;” from Latin acidulus “slightly sour,” a diminutive of acidus (see acid (adj.)).

adj.

1. Slightly acid or sour.