noun

• (historical) A Roman circus.
  "Nero exhibited theſe Spectacles in his own Gardens, impiouſly joining to them the Diverſions of the Cirque, and appearing himſelf publicly in the Habit of a Charioteer, ſitting in his Chariot[…]."
• (geology) A curved depression or natural amphitheatre, especially one in a mountainside at the end of a valley.
  "Whose savage trample thus could pad the dank / Soil to a plash? toads in a poisoned tank, / Or wild cats in a red-hot iron cage— / The fight must so have seemed in that fell cirque."
• (dated or literary) Something in the shape of a circle or ring.
  "Saturn has supplied to the Greeks and Romans the source of a beautiful personification; they have represented him as Time, […] thus with his scythe is he considered to cut down in endless succession every ripened race of man; and as the serpent is annually renewed by the cast of its skin, so is every falling race of man held to be renewed by a young and succeeding progeny; from hence arose the fiction, that Saturn devoured his own children, and hence also is the continuous cirque of imposts at Stonehenge an apt representation of this well imagined emblem."