Probable, possible, likely are comparable when they mean not now certain but such as may be, or may become, true, real, or actual.
Something probable has so much evidence in its support or seems so reasonable that it commends itself to the mind as worthy of belief, though not to be accepted as a certainty; thus, the most probable conclusion from evidence at hand is the one which the weight of evidence supports even though it does not provide proof; the probable thief is the one at whom so much of the evidence points as to give grounds for a presumption that he is guilty; the ” probable life” of a person, in the language of actuaries, is the period during which one half the persons of a given age at a given time will remain alive according to mortality tables.
Something possible is within the powers of performance, attainment, or conception of an agent or agency, especially a human agent or which is within the widest limits of a person’s ability or a thing’s.capacity as determined by nature, necessity, or circumstances or which, though not probable, may happen by chance or is dependent on a contingency.
Something likely (see also APT 2 ) is to all appearances as alleged, suggested, or required; in contrast with probable, likely does not as often or as definitely suggest grounds sufficient to warrant a presumption of truth, but in contrast with possible, it usually implies many more chances in favor of its being true or coming about; thus, the probable murderer is the suspect whose guilt is nearly but not completely established by the evidence; a possible murderer is merely one against whom suspicion is directed for some reason, or one known to have had opportunity; the likely murderer is the one among the possible murderers who, especially from a more or less superficial point of view, has had the strongest motive and the best opportunity, or toward whom the circumstantial evidence most distinctly points as the murderer.
Likely is also often used in the sense of promising because of appearances or ability to win favor nd sometimes in that of suitable because of apparent fitness or adaptation to some end.