1677,
templet "horizontal piece under a girder or beam," probably from Fr.
templet "weaver's stretcher," dim. of
temple, which meant the same thing, from L.
templum "plank, rafter," also "building for worship" (see
temple (1)). The meaning "pattern or gauge for shaping a piece of work" is first recorded 1819 in this form, earlier
temple (1688); the form was altered 1844, probably influenced by
plate, but the pronunciation did not begin to shift until much more recently.