Definition of headspring:
(n) :
A fountainhead; a source.
(n) :
(figurative) A basis or foundation.
(n) :
(gymnastics) A move in which the gymnast places both hands on the mat with the top of the head about 6 inches in front, pushes off with the hands while flipping the legs overhead, and lands on the feet.
(v) :
(gymnastics) To perform a headspring.
(n) :
A spring that sits at the top of a mechanism, pushing the internal parts inward.