tribrach
A metrical foot consisting of three short syllables.
For your foote tribracchus of all three short, ye haue very few trissillables.
Where it comes from
From the Latin tribrachys, from the Ancient Greek τρῐ́βρᾰχῠς (trĭ́brăkhŭs), from τρῐ- (trĭ-, “tri-”) + βρᾰχῠ́ς (brăkhŭ́s, “short”). Compare the French tribraque.
Adapted from the Wiktionary entry tribrach (CC BY-SA 4.0).