Either the spoils of war (as in Jer 21:9) or something won in an athletic contest. Paul employs the latter as a metaphor for salvation (Phil 3:14), the imperishable nature of which he contrasts with the perishable wreaths (made of parsley, celery, etc.) coveted by the athletes of Greece and Rome (1Cor 9:24-25).
Jer 21:9
9Those who stay in this city shall die by the sword, by famine, and by pestilence; but those who go out and surrender to the Chaldeans who are besieging you sha ... View more
Phil 3:14
14I press on toward the goal for the prize of the heavenly call of God in Christ Jesus.
1Cor 9:24-25
24Do you not know that in a race the runners all compete, but only one receives the prize? Run in such a way that you may win it.25Athletes exercise self-contro ... View more