The Collaborative International Dictionary of English v.0.48:

Perseid \Per"se*id\, n. [From Perseus.] (Astron.)
   One of a group of shooting stars which appear yearly about
   the 10th of August, and cross the heavens in paths apparently
   radiating from the constellation Perseus. They are probably
   fragments of Swift's comet of 1862 (III).
   [1913 Webster + Webster 1913 Suppl.]