I. (ˌ)dī-ˈa-səd adjective
or di·acid·ic ˌdī-ə-ˈsi-dik
Date: 1866
: able to react with two molecules of a monobasic acid or one of a dibasic acid to form a salt or ester — used especially of bases
II. noun
Etymology: International Scientific Vocabulary
Date: circa 1929
: an acid with two acid hydrogen atoms