The meaning and origin of the expression: Cock-sure

What's the meaning of the phrase 'Cock-sure'?

Certain. This term has been used in many ways, all with different but related meanings; for example, 'absolutely sure or safe', 'completely dependable', 'sure in one's own mind', etc. The common thread through all of these is certainty.

What's the origin of the phrase 'Cock-sure'?

It is rather ironic that this is one of those term the origin of which we are far from cock-sure about. One point of certainty - it is old. Robert Whittington, mentions it as early as 1520 in his grammatical tract Vulgaria:

"I haue knowen a man or nowe that thought him selfe cocke sure of his intent."

If this term were to follow the pattern of other similes like crystal-clear, ice-cold, dirt-cheap etc., there ought to be a phrase of the form 'as sure as (a) cock'. Unfortunately there isn't and as far as we can tell there never has been. In what ways might a cock be thought of as symbolizing certainty? Some suggestions that have been put forward are, 'as sure as a cock will crow at daybreak', or in reference to the reliable way that a stop tap (stop cock) halts the flow of water. These are little more than guesses - in fact we can't be sure.

What we do know is that it doesn't refer to the word 'cocky' meaning 'opinionated and sure of oneself'. That is known by 1770 but is pre-dated by many occurrences of 'cock-sure' in print. Nor can the opinion put forward in Francis Grose's Classical Dictionary of the Vulgar Tongue, 1811, be correct. He said:

"COCK-SURE. Certain: a metaphor borrowed front the cock of a firelock, as being much more certain to fire than the match."

Again, the term pre-dates the firelock musket, or any other sort of lock musket, e.g. flintlock.

See other phrases first recorded by Captain Francis Grose.