According to Merriam-Webster Unabridged,
possible can be a noun, adjective and adverb:
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possible
Function: noun
1 a : POSSIBILITY, POTENTIALITY -- usually used in plural <all the infinite number of possibles -- Jonathan Edwards> b : all that can be done : BEST <had done my possible ... to gratify you -- Robert Southey>
2 possibles plural : necessary things (as supplies, equipment, money) <the hunters departed, each to look after his traps and possibles -- Mayne Reid>
3 : the highest attainable score for a number of rounds fired in target shooting; broadly : the highest attainable score in a competition
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