Archaism

This is an archaism.

Isn't that an archaism?

It is not improbable that, like English poets of a later time, Layamon affected a certain archaism in language, as giving greater beauty and interest to his style.

In this text, the word "methinks" appears to be a deliberate archaism.

He had the fastidiousness, the preciosity, the love of archaisms, of your true decadent.