  The D-term is a particle property defined, similarly to the mass and spin,
through matrix elements of the energy-momentum tensor. It is currently not
known experimentally for any particle, but the D-term of the nucleon can be
inferred from studies of hard-exclusive reactions. In this work we show that
the D-term of a spin-1/2 fermion is of dynamical origin: it vanishes for a free
fermion. This is in pronounced contrast to the bosonic case where already a
free spin-0 boson has a non-zero intrinsic D-term as shown in an accompanying
work. We illustrate in two simple models how interactions generate the D-term
of a fermion with an internal structure, the nucleon. All known matter is
composed of elementary fermions. This indicates the importance to study this
interesting particle property in more detail, which will provide novel insights
especially on the structure of the nucleon.
