1) Of twisting 
• (a.) Of or pertaining to torsion; resulting from torsion, or the force with which a thread or wire returns to a state of rest after having been twisted round its axis; as, torsional force.
Tor'sion·al adjective Of or pertaining to torsion; resulting from torsion, or the force with which a thread or wire returns to a state of rest after having been twisted round its axis; as, torsional force.