The word 'tween' is a modern linguistic creation, a deliberate truncation of the common English preposition 'between'. This process of clipping, where a longer word is shortened while retaining its core meaning, became popular in 20th-century marketing and media to create catchy, youthful terms. It was specifically coined to label the demographic and developmental stage 'between' childhood and adolescence. The logic is transparent and functional: the morpheme directly imports the sense of being in an intermediate or transitional phase, applying it neatly to a person's age.

Structure: tween (between) The morpheme 'tween' is a clipped form of the English word 'between', originating from Middle English 'betwene', itself from Old English 'betwēonum'. It functions as a lexical root representing the concept of an intermediate state or position.