A description applied to a girl with large breasts, a large butt, but who is otherwise thin and scrawny. The term comes from the fact that she is distributed weight-wise similar to a flywheel, implying that if she started to fall she would roll.
Man, you should've seen this girl: skinny but with a gorgeous rack a huge ass. She was a total flywheel.
by Notmiefault February 19, 2011
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Adjective phrase:

A descriptor applied to a person who functions well but is "not quite right in the head," as indicated by small but noticeable eccentricites of behavior to which said person is oblivious.
"Sure, Jeff is great guy, but he leaves the impression that deep down dude's missing a flywheel."
by Neil Ogism April 17, 2010
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