NOUN (1)

1. a medieval brass instrument with a clear shrill tone;


VERB (2)

1. blow the clarion;

2. proclaim on, or as if on, a clarion;


ADJECTIVE (1)

1. loud and clear;
- Example: "a clarion call"

The Collaborative International Dictionary of English v.0.48:

Clarion \Clar"i*on\, n. [OE. clarioun, OF. clarion, F. clairon,
   LL. clario, claro; so called from its clear tone, fr. L.
   clarus clear. See Clear.]
   A kind of trumpet, whose note is clear and shrill.
   [1913 Webster]

         He sounds his imperial clarion along the whole line of
         battle.                                  --E. Everett.
   [1913 Webster]

U.S. Gazetteer (1990):

Clarion, IA (city, FIPS 13620)
  Location: 42.73205 N, 93.73213 W
  Population (1990): 2703 (1264 housing units)
  Area: 7.1 sq km (land), 0.0 sq km (water)
  Zip code(s): 50525
Clarion, PA (borough, FIPS 13800)
  Location: 41.21015 N, 79.38045 W
  Population (1990): 6457 (1917 housing units)
  Area: 3.9 sq km (land), 0.1 sq km (water)
  Zip code(s): 16214

Moby Thesaurus II by Grady Ward, 1.0:

165 Moby Thesaurus words for "clarion":
   English horn, alpenhorn, alphorn, althorn, alto horn, bagpipe,
   ballad horn, baritone, bass horn, bassoon, bay, beep, bell, blare,
   blast, blat, block flute, blow, blow a horn, blow the horn,
   bombard, bourdon, brass choir, brass wind, brass-wind instrument,
   brasses, bray, bugle, bugle call, bugle horn, call to arms,
   call-up, carillon, catchword, cello, claribel, clarinet,
   clarion call, clear, cloudless, concert flute, conscription,
   cornet, cornet-a-pistons, corno di caccia, cornopean, cromorna,
   cymbel, diapason, doodle, double-bell euphonium, double-tongue,
   dulciana, euphonium, exhortation, fife, fine, flute, flute stop,
   foundation stop, fourniture, gamba, gedeckt, gemshorn,
   go for broke, gung ho, harmonic flute, helicon, honk, horn,
   hunting horn, hybrid stop, key trumpet, koppel flute, larigot,
   levy, lip, lituus, lur, mellophone, melodia, mixture, mobilization,
   muster, mutation stop, nazard, oboe, octave, ophicleide,
   orchestral horn, organ stop, peal, piccolo, pipe, pleasant,
   plein jeu, pocket trumpet, posaune, post horn, principal, quint,
   quintaten, rainless, rally, rallying cry, rank, ranket, rebel yell,
   recruitment, reed stop, register, rohr flute, sackbut, saxhorn,
   saxtuba, serpent, sesquialtera, shawm, shriek, slide trombone,
   sliphorn, slogan, sound, sound a tattoo, sound taps, sousaphone,
   spitz flute, squeal, stop, stopped diapason, stopped flute,
   string diapason, string stop, sunny, sunshiny, tenor tuba, tierce,
   tongue, toot, tootle, tremolo, triple-tongue, tromba, trombone,
   trumpet, trumpet call, tuba, tweedle, twelfth, unclouded,
   unda maris, undarkened, valve trombone, valve trumpet, vibrato,
   viola, voix celeste, vox angelica, vox humana, war cry, war whoop,
   watchword, whistle, wind, wind the horn