an instance of archaic usage; esp an archaic word or expression
the use of archaic diction or style
something outmoded or old-fashioned
The question is whether these hallowed archaisms are only a surface phenomenon, which a sensible modernization of Parliament would easily sweep away — Anthony Arblaster
archaistic /-ʹistik/ adj
[via Latin from Greek archaïsmos, from archaios ancient]