The noun possibility has 4 senses (first 4 from tagged texts)
1. (21) possibility -- (a future prospect or potential; "this room has great possibilities")
2. (18) possibility, possibleness -- (capability of existing or happening or being true; "there is a possibility that his sense of smell has been impaired")
3. (12) hypothesis, possibility, theory -- (a tentative theory about the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena; "a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was accepted in chemical practices")
4. (6) possibility, possible action, opening -- (a possible alternative; "bankruptcy is always a possibility")