A pseudovector boson is a vector boson that has even parity, whereas "regular" vector bosons have odd parity. There are no fundamental pseudovector bosons, but there are pseudovector mesons.
In relation to the Higgs boson
Feynman diagram of the fusion of two electroweak vector bosons to the scalar Higgs boson, which is a prominent process of the generation of Higgs bosons at particle accelerators. (The symbol q means a quark particle, W and Z are the vector bosons of the electroweak interaction. H0 is the Higgs boson.)
The space of spin states therefore is a discrete degree of freedom consisting of three states, the same as the number of components of a vector in three-dimensional space. Quantum superpositions of these states can be taken such that they transform under rotations just like the spatial components of a rotating vector[citation needed] (the so-called 3 representation of SU(2)). If the vector boson is taken to be the quantum of a field, the field is a vector field, hence the name.
The boson part of the name arises from the spin-statistics relation, which requires that all integer spin particles be bosons.