Yes, PURITAN is a Scrabble word!

Letter values in Scrabble US: P 3, U 1, R 1, I 1, T 1, A 1, N 1.

Is it a valid word?

PURITAN is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a member of a group of English Protestants who in the 16th and 17th centuries thought that the Protestant Reformation under Elizabeth was incomplete and advocated the simplification and regulation of forms of worship
someone who adheres to strict religious principles; someone opposed to sensual pleasures
a person excessively concerned about propriety and decorum