  We report high-pressure $^{77}$Se NMR studies on FeSe single crystals that
reveal a prominent inhomogeneous NMR linewidth broadening upon cooling, with
the magnetic field applied along the tetragonal [110] direction. The data
indicate the existence of short-range-ordered, inhomogeneous electronic
nematicity, which has surprisingly long time scales over milliseconds. The
short-range order survives temperatures up to $8$ times the structural
transition temperature, and remains robust against pressure, in contrast to the
strong pressure-dependence of the orbital ordering, structural transition, and
the ground state magnetism. Such an extended region of static nematicity in the
($P$,$T$) space of FeSe indicates an enormously large fluctuating regime, and
provide fresh insights and constraints to the understanding of electronic
nematicity in iron-based superconductors.
