adjective
- equally good and bad, likely and unlikely, favorable and unfavorable, etc.: a fifty-fifty chance of winning.
adverb
- in an evenly or equally divided way: The board voted fifty-fifty on the merger.
- go fifty-fifty (on), to share equally in the cost, responsibility, or profits (of): We went fifty-fifty on the dinner check.
adjective, adverb
- informal shared or sharing equally; in equal parts
see under under go halves.