contraction of between.
Also tween, tweeny. a youngster between 10 and 12 years of age, considered too old to be a child and too young to be a teenager.
Origin of 'tween
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Related Words for 'tweenbetwixt, amid, among, halfway, in, inserted, intervening, mid, midway, within, amidst, medially
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012