[See COTTEREL sb.] A pin, key, wedge or bolt that fits into a hole and fastens something in its place.
The term is variously applied to: (a) a small pin that fits into a hole in a bar, bolt, or the like, and keeps something in its place; sometimes a split pin (see quot. 1887); (b) a bolt passing through a hole (in a shutter, etc.) and secured on the inside, usually by a smaller pin; (c) a ‘key’ or wedge-shaped piece of wood or metal used for tightening up or fastening parts of machinery, as the strap-head to the connecting rod, for holding together links of a broken chain, etc.
1649. [implied in cotter-hole and COTTER v.1].
1747. Hooson, Miner’s Dict., s.v. Boring, I do not at all like Sockets and Cotters.
1790. E. Marshall, Rur. Econ. Midl. C.. Gloss., Cotter, an iron key to a bolt.
1833. J. Holland, Manuf. Metal, II. 209. A coupling bar, bolted at both ends with steel cottars.
1842. Jrnl. R. Agric. Soc., III. II. 350. This simple little contrivance is much preferable to pins and cotters, which are apt to shake out, or to be neglected in the fastening.
1856. Ann. Reg., 54. There was an outside shutter fastened by a cotter within.
1880. Daily News, 20 April, 2/5. The use of the cotters was to tighten up the bracings.
1887. S. Cheshire Gloss, Cotter, an iron pin or peg, split from the bottom into two arms diverging at a small angle…. After passing through the hole the arms of course spring apart again, and the pin is secured in its place.
b. Comb., as cotter-hole; cotter-drill, cotter-file, tools for making the holes for cotters to fit into; cotter-patch, see quot. 1884. cotter-pin, a cotter, or a pin to keep a cotter in its place.
1649. Blithe, Eng. Improv. Impr. (1653), 67. Through … the Wood, the tange of the Coulter must come, with a Cotter-hole in it above.
1881. Greener, Gun, 85. The thimble is retained in the barrel during the discharge by a cotter pin passing through the barrel, the base of the thimble, and the stock.
1884. Cheshire Gloss., Cotter-patch, salt-making term. An iron patch put at one corner of a salt-pan, and fastened with a cotter, to cover the letting out place.
1891. Daily News, 24 Jan., 3/7. The Mohawk Cycling Company have adopted the principle of fixing the pedals to the cranks by means of a cotter pin instead of a nut.
