trivium

noun2

1. •
   (historical) The lower division of the liberal arts in a medieval university; grammar, logic, and rhetoric.

   • Surely some demon must possess the lad, / Who showed more wit than ever school-boy had, / And learned his Trivium thus without the rod; / But Alcuin said it was the grace of God. — 1873
2. •
   The three anterior ambulacra of echinoderms, collectively.