10 letters · 19 points in Scrabble
noun a man skilled in equitation
adjective of or relating to or composed of knights
adjective of or relating to or featuring horseback riding
originUltimately from Latin equester (“of or pertaining to equestrians/cavalry”) + -ianus (“-ian, related to”, adjective marker), from equus (“horse”).
Etymology from Wiktionary, CC BY-SA 3.0