Surprisingly, tween has differing definitions depending on the dictionary. All agree that the term is referring to adolescents, either boy or girl, ages eleven and twelve. However, some dictionaries say tween is an abbreviated form of preteen, while others say it is an abbreviated form of tweenager.
A tweenager is listed as a child between the ages of ten and fourteen, someone who is almost a teenager or a new teenager.
An alternative for tween is listed as tweenie.
A preteen has general age range of nine to twelve.
Yet another form of the word is preteen-ager. Though we aren’t exactly sure why this form exists.
Be aware that preteen is spelled with a hyphen outside the United States.
It should also be noted that tween can also be a shortened form of between. It does not require the initial apostrophe for the missing letters.
Interestinly, JR Tolkien used the word tween to describe hobbits in their twenties who were reckless. In this mythical species an adult was 33. It seems that the two terms were created independently. We do not owe the current usage of tween to Tolkien, and he certainly was not referencing tweens as we know the word.
Unsuspecting dads, moms and grandparents who took their teen and tween offspring to the show, left the performance with a clear idea of what today’s teen pop sounds like … the unified voices of 4,000 10-, 11-, 12-, 13-, 14- and 15-year-old girls screaming as loud as is humanly possible. [The Albany Herald]