Entry 1 sense Webster, 1913 Clarion /klĕr'-ē-ən/ · Clar·i·on · IPA /ˈklæ.ɹi.ən/ 01 n. A kind of trumpet, whose note is clear and shrill. 1. A kind of trumpet, whose note is clear and shrill. “He sounds his imperial clarion along the whole line of battle.” — E. Everett.