Any venomous or deadly thing.
This creatures looks like a strange cross between a rooster and a dragon or snake. It's gaze can turn a person to stone. Often in legend this creature is confused with the Basilisk.
monster hatched by a reptile from a cock's egg; able to kill with a glance
a serpent, hatched from a cock's egg, that can kill with a glance
a snake with the power to kill with a glance, hatched from a cock's egg
Isaiah 11:8 kjv Mythological serpent
A cockatrice is a legendary creature, "an ornament in the drama and poetry of the Elizabethans" (Breiner). The cockatrice was invented in the late twelfth century based on a hint in Pliny's Natural History, as a duplicate of the basilisk or regulus, in appearance resembling a giant rooster, with a lizard-like tail. It was supposed to be born from an egg laid by a cockThis impossibility is at the root of the originally pejorative term "Cockney" ("cock's egg") for a Londoner. and incubated by a toad or serpent.
In the Dungeons & Dragons fantasy role-playing game, the cockatrice is a small avian magical beast. Any creature that a cockatrice bites can be permanently turned to stone.