Definition of tweens:
(n) :
A child, especially a girl, in the age range between middle childhood and adolescence, normally between eight and thirteen years of age.
(adj) :
Of or relating to tweenagers.
(n) :
(animation) An action of tweening (inserting frames for continuity); a sequence of frames generated by tweening.
(v) :
(cinematography) To generate intermediate frames in an animated sequence so as to give the appearance of smooth movement.
(n) :
(rare) A number or age in the twenties (plural only), or a person of that age.