Antonyms of positive :
disconfirming, electronegative, electroneutral, negative, neutral, neutralised, diffident, gram-negative, counter, incertain, unsure, viewless, uncharged, timid, uncertain, minus, deniable, antagonistic, shy, informal, perverse, neutralized, disadvantageous, accountable, constitutional, gentle, lowly, responsible, complaisant, contingent, humble, meek, submissive, compliant, docile, lenient, mild, yielding, conditional, ductile, limited, captious, carping, caviling, censuring, critical, faultfinding, hypercritical, overcritical, belittling, contemptuous, disdainful, disparaging, scornful, slighting, adverse, depreciative, depreciatory, derogatory, disapproving, inappreciative, unappreciative, uncomplimentary, unfavorable, unflattering, unfriendly, hesitant, indecisive, vacillating, wavering, unassuming, doubtful, dubious, controversial, debated, disputed, iffy, inconclusive, ambiguous, equivocal, academic, hypothetical, speculative, theoretical, answerable, arguable, contradictable, controvertible, debatable, disputable, doubtable, moot, negotiable, problematic, questionable, refutable.
Examples of usage:
" At this time," he said, " it will scarcely do to be positive on some things. "Ashton-Kirk, Investigator", John T. McIntyre.
My orders are positive." "The Circular Staircase", Mary Roberts Rinehart.
When I pressed him for an explanation, he was unable to give any definite reasons, except that he felt positive it could be done. "Edison, His Life and Inventions", Frank Lewis Dyer and Thomas Commerford Martin.