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1.
this is a person who starts dating someone after another person stops dating that person. the ex has already been with that person so the new person is their cast off
did u hear Shelly's going out with Jamie? o well, i was with him first! she's my cast off now!
by blondie67 June 01, 2005
 
2.
A man or woman with a reputation who has been rejected multiple times by multiple people for unknown reasons.
Who is that guy? He's a castoff from UofM.
by bagitbabe August 23, 2008