A covariant tensor of rank 1, more commonly called a one-form (or "bra").
Covariant Vector
See also
Bra, Contravariant Vector, Contravariant Tensor, Ket, One-Form, VectorExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Covariant Vector." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/CovariantVector.html