What is an augury? (From Sophocles' Antigone)

Augury is a divination from omens. Here it refers to the ritual sacrifice of an animal and the examination of its organs for an indication of the future.

The divination of my arts shall tell. / Sitting upon my throne of augury, / As is my wont, where every fowl of heaven / Find harborage, upon mine ears was borne / A jargon strange of twitterings, hoots, and screams . . .

Teiresias, from Sophocles' Antigone.