conjecture, supposition, surmise, speculation, guess, theory, possibility, postulate, hypothesize, more...

certainty, fact, truth, reality, confirmation

null hypothesis, more...

null, alternative, second, general, original, third, scientific, latter, nebular, reasonable, plausible

conjecture or guess,   an unproven theory,   an educated guess,   scientific guess,   it is suggested,   offered theories,   a theory,   current theory,   theory idea,   theorem word