1) Athletic competition 2) Athletic contest 3) Athletics 4) Bout before the biggie 5) Bout before the main event 6) Bout on boxing card 7) Earlier contest 8) Early bout 9) Early boxing match 10) Early game in a tournament 11) Early heat 12) Early match 13) Early race or round 14) Early round 15) Early stage of a tourney Found on https://www.crosswordclues.com/clue/prelim
Short for preliminary, also called heats. Those races in which swimmers qualify for the championship and consolation finals in the events. Found on https://www.encyclo.co.uk/local/22351