Zipper
Whitcomb Judson patented it - but the man who actually made it work spent a decade fixing his mistake, and neither of them named it.
In 1893, at the Chicago World's Fair, engineer Whitcomb Judson unveiled his 'clasp-locker' - a row of hooks and eyes yanked together by a sliding clasp. Designed to replace the tedious button-hook boots of the era, the sliding clasp as first shown was finicky and didn't catch on right away.
Gideon Sundback, a Swedish-American engineer hired by Judson's own company, spent years redesigning the mechanism from the ground up. Sundback ditched the hooks entirely for interlocking teeth, precisely spaced, engaging and releasing in one continuous motion. The resulting design was patented as the 'Separable Fastener' in 1917.
It still didn't have a name people wanted to say out loud. That arrived in 1923, when B.F. Goodrich put Sundback's fastener on a new line of rubber galoshes that were named for the sound they made - a quick, satisfying zzzip.
Whitcomb Judson did not invent the zipper as we know it -- he invented an unreliable hook fastener that failed commercially, and Gideon Sundback's later redesign is the mechanism actually in use today.