tribrach

noun3

1. •
   A metrical foot consisting of three short syllables.

   • For your foote tribracchus of all three short, ye haue very few trissillables. — 1589
2. •
   A figure or object having three arms or branches.

   • An optical plummet, built into either the tribrach or alidade of total station instruments, permits accurate centering over a point. — 2006
3. •
   A tribrachial prehistoric flint implement.

   • A singular instrument chipped out of flint, like three celts conjoined…, so as to form a sort of tribrach. — 1897