Noun
(sports) A person who plays at two positions, not good enough at either to be restricted to it.
(tennis) A shot that is hit between the legs.
(informal) A tweenager.
(computing) A computing device that is smaller than a traditional laptop, but larger than a PDA.
(boxing) A boxer in various newcomer weight classes whose names often contain "super", "light" or "junior".
(professional wrestling slang) A professional wrestler who is neutral or morally ambiguous; neither a face nor a heel, or showing no favoritism to either allegiance.
(cinematography) A person, machine or piece of software that performs tweening.
(informal) A film that falls between two genres (and thus may not be easily marketed).
Source: en.wiktionary.orgAnybody that shoots a hook shot, whatever hand, I jump up and cheer because it's the easiest shot, it's the best tweener shot. Tom Heinsohn
His attitude and his modus operandi- using heel tactics in a face role - would come to define the tweener role in professional wrestling. Source: Internet
Mills fell all the way to the seventh round of last year’s draft due to off-field concerns and questions about his tweener position in the NFL. Source: Internet