- One who reduces religion to strict interpretation of core or original texts.
- (finance) A trader who trades on the financial fundamentals of the companies involved, as opposed to a chartist or technician.
- (Christian) Originally referred to an adherent of an American Christian movement that began as a response to the rejection of the accuracy of the Bible, the alleged deity of Christ, Christ's atonement for humanity, the virgin birth, and miracles. These points were first listed in a book series entitled "The Fundamentals: A Testimony to the Truth" published in 1909 and affirmed by the PCUSA in its 1910 Minutes of the General Assembly.
- (pejorative) A fundamentalist Christian (also fundie or fundy)