Perseid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One of a shower of meteors that appears to originate in the vicinity of the constellation Perseus during the second week of August.

from The Century Dictionary.

• noun The flock of Perseids is of great extent and moves in a path apparently coincident with that of Tuttle's comet of 1862, and now forms almost a complete oval ring around the sun. It gives us, therefore, more or less of a shower each year, beginning in the latter part of July and lasting till late in August, but most abundant about August 12. The Perseids are for the most part yellowish, and move with medium velocity, not as swiftly as the bluish Leonids, but more swiftly than the Bielids.
• noun One of the August meteors: so named because they seem to radiate from the constellation Perseus.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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 1862 (III).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun astronomy Any of the meteors in a meteor shower that appears to come from the constellation Perseus.