In theoretical physics, the D-term is the final term in the expansion of a vector superfield over fermionic coordinates.
A superfield is a field that depends on all coordinates of the superspace, which is the coordinate space of a theory exhibiting supersymmetry.
4D N = 1 global supersymmetry may be written using a superspace involving four extra fermionic coordinates
Every superfield may be expanded with respect to the new fermionic coordinates.
Manifestly supersymmetric Lagrangians may also be written as integrals over the whole superspace.
Some special terms, such as the superpotential, may be written as integrals over
s only, which are known as F-terms, and should be contrasted with the present D-terms.