Gnome

Gnomes, Gnomenfolk or the Forgotten Folk as they were sometimes known, are a humanoid race of small people 2 – 3.5 ft. in height (3.9 ft. is the tallest ever recorded gnome) that live mostly underground.
The gnomes work complex tunnel systems, and build elaborate cities in the rock. They delve deep below the surface and under mountains as persistent miners, and are inquisitive and inventive engineers.
Gnomes are altogether more peaceful than dwarves, yet live often far removed from other civilized people.
Also: Gnomenkind or Gnomenfolk