Ar'cha-ism, n.

n. [Fr. archaisme, from Gr. ἀρχαῖος, ancient, ἀρχή, beginning. See ARCH, a.]

1. An ancient or obsolete word, expression, or idiom. Watts.
2. Antiquity of style or use.

A select vocabulary corresponding (in point of archaism and remoteness from ordinary use) to our scriptural vocabulary. De Quincey.