Zipper Definition: Devices consisting of two opposite series of members adapted to be attached one on each side of an aperture in some article and to interlock so as to close the aperture upon the slide being operated in one direction, or to separate so as to leave the aperture open upon the slide being operated in the opposite direction. Editor's note: we didn't make this up! It's from a 1932 trademark case of the Supreme Court of Canada called Lightning Fastener Co. Ltd. V. Canadian GoodrichCo. Ltd. Find you are constantly looking up definitions? Try our search provider (works in most modern browsers) If you find an error or omission in Duhaime's Legal Dictionary, or if you have legal term suggestion, we'd love to hear from you!