Merriam-Webster's Collegiate® Dictionary, 11th Edition
RUNAWAY
I. noun
Date: 1547
one that runs away from danger, duty, or restraint ; fugitive , the act of running away out of control, a one-sided or overwhelming victory,
II. adjective
Date: 1548
1. running away ; fugitive , leaving to gain special advantages (as lower wages) or avoid disadvantages (as governmental or union restrictions) , accomplished by elopement or during flight, won by or having a long lead , subject to uncontrolled changes , being or operating out of control