What is the origin of the word 'cock'?

Answer 1

The word appears to be of Germanic origin. The original meaning was "a male bird".

The term was later applied to aggressive people because of the similarity of behavior to the fighting birds. This is where the word "cocky" comes from.

Another characteristic of the birds was upright posture. Because of this, the word came to mean "something that sticks up". This is where we get the expression "cocked ear".

The term also was applied to a spout, since a spout is something that sticks up. In modern usage, a radiator or a water heater is said to have a drain cock.

The slang use of the word for penis probably originates somewhere between the aggressive bird meaning and the spout meaning. A penis is called a cock because it is said to resemble a bird, and because the rooster is a symbol of masculinity in some cultures. Similarly, in Spanish a penis is commonly called a pajaro (bird), a pavo (turkey), or a polla (chicken). Perhaps the most bird-like penises are those that tend to tilt or curve slightly southward when erect (similar to the natural curvature of a rooster neck and head), the pubic hair at the base of the penis could also be said to resemble the ring or collar of feathers displayed by some roosters. The large wattles (i.e. the fleshy sack) that form on both turkeys and some roosters can also be said to resemble a man's scrotum.

Answer 2

Cock is used as a term used for male birds, like chickens, peacocks etc. Also as a tap, or faucet, as in stopcock.