1. [n]  a spear thrown as a weapon or in competitive field events
2. [n]  an athletic competition in which a javelin is thrown as far as possible

JAVELIN is a 7 letter word that starts with J.

1. \Jave"lin\, n. [F. javeline; akin to Sp. jabalina, It.
   giavelina, and F. javelot, OF. gavlot. Cf. {Gavelock}.]
   A sort of light spear, to be thrown or cast by thew hand;
   anciently, a weapon of war used by horsemen and foot
   soldiers; now used chiefly in hunting the wild boar and other
   fierce game.
   
         Flies the javelin swifter to its mark, Launched by the
         vigor of a Roman arm?                    --Addison.
   
   

2. \Jave"lin\, v. t.
   To pierce with a javelin. [R.] --Tennyson.
   
   

(1.) Heb. hanith, a lance, from its flexibility (1 Sam. 18:10, 11; 19:9, 10; 20:33).

(2.) Heb. romah, a lance for heavy-armed troops, so called from its piercing (Num. 25:7). (See ARMS.)