Purist

Many Americans insist that immigrants speak English, but wouldn't a true language purist insist on Old English, wynns, thorns, edhs and all?

I'm a purist.

He's a language purist.

Tom is a radical linguistic purist.

He was the first to play for money, a practice which got him ousted from the purist U.S. Lawn Tennis Association.

One of the difficulties that plague conversations about industrial music is that the genre has come to include (to the chagrin and outright denial of some purists) anything from gentle synthesized droning to metal-inspired riffage.