A (Covariant) 1-Vector denoted . The bra is Dual to the Contravariant Ket, denoted . Taken together, the bra and Ket form an Angle Bracket (bra+ket = bracket). The bra is commonly encountered in quantum mechanics.
See also Angle Bracket, Bracket Product, Covariant Vector, Differential k-Form, Ket, One-Form