What is "underheated"

Usage examples of "underheated".

There had been long rides in a rattling pickup, endless hours in smelly paddocks, loud voices, the gnaw of real hunger, the cries of fretful babies, the chill of underheated rooms.

The air was cool, underheated, spiced with the scent of carnations though none were in view.

But then gradually it dawned on him that he had left the house and gone to his lonely, underheated cubicle for a definite reason.

They always fogged when he came back outside from the over or underheated bus, and he didn't have time to fuss with them.