A bolt, wedge, key, or pin inserted through a slot in order to hold parts together. (noun)
A cotter pin. (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "cotter" in a sentence
"a cotter is a thief; he that lifts a drove from a Sassenach laird is a gentleman-drover."
"The fire crackles and blazes, so that we do not mind the wind, though there are no blinds to the kitchen, and if we do not "cotter" the shutters, we look out upon the black night, and the tall Scotch pine that has been tossed so wildly for so many years, and is not torn down yet."
"It patches waders, boats, holds together broken rods, makes pretty nifty sunglass retainers (like above), and just a week or so ago I actually used duct tape to hold my oar lock in place after a friend had straightened the cotter pin holding it in place. 12 inches if Duct tape literally saved an entire day of fishing."