cockatrice is a legendary creature, essentially a two-legged dragon with a rooster's head. "An ornament in the drama and poetry of the Elizabethans", Laurence Breiner described it. It featured prominently in English thought and myth for centuries.
The cockatrice was first described in its current form in the late twelfth century. The Oxford English Dictionary gives a derivation from Old French cocatris, from medieval Latin calcatrix, a translation of the Greek ichneumon, meaning tracker.
According to Alexander Neckam's De naturis rerum (ca 1180), the cockatrice was supposed to be born from an egg laid by a cock and incubated by a toad; a snake might be substituted in re-tellings.
It is thought that a Cock egg
would birth a cockatrice, and could be prevented by tossing the
yolkless egg over the family house, landing on the other side of the
house, without allowing the egg to hit the house.
Its reputed magical abilities include turning people to stone or killing them by either looking at them—"the death-darting eye of Cockatrice"—touching them, or sometimes breathing on them.
It was repeated in the late-medieval bestiaries
that the weasel is the only animal that is immune to the glance of a
cockatrice. It was also thought that a cockatrice would die instantly
upon hearing a rooster crow, and according to legend, having a cockatrice look itself in a mirror is one of the few sure-fire ways to kill it.
Like the head of Medusa, the cockatrice's powers of petrification were thought still active after death.