Source : Webster's Revised Unabridged Dictionary (1913)

Erectness \E*rect"ness\, n.
   Uprightness of posture or form.

Source : WordNet®

erectness
     n 1: the property of being upright in posture [syn: {uprightness}]
     2: position at right angles to the horizon [syn: {verticality},
         {verticalness}, {uprightness}]