I. run ‧ a ‧ way 1 /ˈrʌnəweɪ/ BrE AmE adjective [only before noun]
1 . a runaway vehicle or animal is out of control:
a runaway horse
2 . happening very easily or quickly, and not able to be controlled:
The film was a runaway success.
runaway inflation
a runaway victory
3 . a runaway person has left the place where they are supposed to be ⇨ run away
II. runaway 2 BrE AmE noun [countable]
someone, especially a child, who has left home without telling anyone and does not intend to come back
⇨ run away at ↑ run 1