Eggcorn Forum

A person who is “cocksure” is cocky, excessively confident. Many people who use this word assume that both “cocksure” and “cocky” have something to do with strutting roosters. They are partly right. By the 1760s “cocky,” derived from “cock,” used the vanity of the cock of the walk to nail a certain kind of arrogance with an agricultural metaphor. The term “cocksure,” however, probably doesn’t rely on an image of the master and mister of the barnyard hens. “Cocksure” was around for two hundred years before it picked up the sense of excessive, priggish confidence that eventually drove out all the other meanings of the word. Interestingly, it gained this meaning in the eighteenth century, about the same time that “cocky” appeared in the language, suggesting that some people might have associated the two words.

Before transforming itself into an insult, “cocksure” was employed to refer to something that was dependable, certain, secure. Holinshed’s Chronicles, that famous source of Shakespeare’s historical knowledge, has this phrase: “The princes court would not haue beene kept there, vnlesse the place had beene taken to be cocksure.”

As the OED observes, the conjecture that cocksure makes “some allusion to cockish, cocky, with reference to ‘pert self-confidence’ ... is not historically tenable.” Where, then, does the original meaning of “cocksure” come from? Possibly the word makes allusion to the cock, i.e. the tap, in a barrel of ale. The barrel’s cock had to fit snugly (i.e., it had to be sure) or the liquid would leak out. Alternately, there may be some connection between “cocksure” and the cock of a gun. The term “cock” for the firing lever of a gun appeared about the same time as “cocksure” and the dangers of a gun with an unsure cock are obvious.

If “cocksure” does refer to the cock in a barrel or the cock of a gun, then “cocksure” is a hidden eggcorn for English speakers who associate the word with braggart chanticleers.