The Collaborative International Dictionary of English v.0.48:

Leonid \Le"o*nid\ (l[=e]"[-o]*n[i^]d), n. [From Leo: cf. F.
   l['e]onides, pl.] (Astron.)
   One of the shooting stars which constitute the star shower
   that recurs near the fourteenth of November at intervals of
   about thirty-three years; -- so called because these shooting
   stars appear on the heavens to move in lines directed from
   the constellation Leo.
   [1913 Webster]