From Hull AWE
A cockerel is precisely defined as a young male bird of the domestic fowl, Gallus domesticus. When full grown, it becomes a cock: before it is a cockerel, it is a chick.
- In some circles, cockerel is used as a euphemism for what is properly, in farming and biological, and particularly ornitholigical, terms, a cock - as this word is also used informally to mean 'penis', a usage which is felt by some people to be tabu. That should not stop you using the word entirely correctly, in formal English, for its accurate meaning in ornithology, agriculture and biology generally. See also rooster.