Puritan  —n. 1 (puritan) hist. Member of a group of english protestants who sought to simplify and regulate forms of worship after the reformation. 2 purist member of any party. 3 strict observer of religion or morals. —adj. 1 (puritan) hist. Of the puritans. 2 scrupulous and austere in religion or morals.  puritanism n. [latin: related to *pure]