Archaism

Ar·cha·ism

Archaism

n.
  1. An ancient, antiquated, or old-fashioned, word, expression, or idiom; a word or form of speech no longer in common use.
  2. Antiquity of style or use; obsoleteness.
    A select vocabulary corresponding (in point of archaism and remoteness from ordinary use) to our Scriptural vocabulary.