Dictionary: zipper (zĭp'ər) n.
A fastening device consisting of parallel rows of metal, plastic, or nylon teeth on adjacent edges of an opening that are interlocked by a sliding tab.
tr. & intr.v., -pered, -per·ing, -pers.
To fasten or unfasten or become fastened or unfastened with a zipper; zip.
[Originally a trademark.]
WORD HISTORY Trademark laws exist to prevent the appropriation of words like zipper. Registered in 1925, zipper was originally a B.F. Goodrich trademark for overshoes with fasteners. A Goodrich executive is said to have slid the fastener up and down on the boot and exclaimed, “Zip 'er up,” echoing the sound made by this clever device. Zip already existed as both a noun and verb referring to a light sharp sound or to motion accompanied by that kind of sound (zip was first recorded as a noun in 1875; as a verb, in 1852). Both words were imitations of the sound made by a rapidly moving object. As the fastener that “zipped” came to be used in other articles, its name was used as well. B.F. Goodrich sued to protect its trademark but was allowed to retain proprietary rights only over Zipper Boots. Zipper itself had moved into the world of common nouns.
A fly is a zipped, Velcro or buttoned opening in trousers, shorts and other garments covering the groin. Opened by male to facilitate urination, and by both genders to allow garments to be taken on or off with greater ease.