All improbable antonyms

adj improbable

• believable — Something that is believable makes you think that it could be true or real.
• likely — probably or apparently destined (usually followed by an infinitive): something not likely to happen.
• plausible — having an appearance of truth or reason; seemingly worthy of approval or acceptance; credible; believable: a plausible excuse; a plausible plot.
• real — true; not merely ostensible, nominal, or apparent: the real reason for an act.
• ostensible — outwardly appearing as such; professed; pretended: an ostensible cheerfulness concealing sadness.
• possible — that may or can be, exist, happen, be done, be used, etc.: a disease with no possible cure.
• probable — likely to occur or prove true: He foresaw a probable business loss. He is the probable writer of the article.
• tenable — capable of being held, maintained, or defended, as against attack or dispute: a tenable theory.
• probably — in all likelihood; very likely: He will probably attend.
• ordinary — of no special quality or interest; commonplace; unexceptional: One novel is brilliant, the other is decidedly ordinary; an ordinary person.