doubtful,dubious,improbable,unimaginable,unlikely.

Prepositions:

(When apparent is used in the sense of evident): His guilt is apparent in every act to all observers.


APPEAR.

Synonyms:

have the appearance or semblance,look,seem.

Appear and look refer to what manifests itself to the senses; to a semblance or probability presented directly to the mind. Seem[53] applies to what is manifest to the mind on reflection. It suddenly appears to me that there is smoke in the distance; as I watch, it looks like a fire; from my knowledge of the locality and observation of particulars, it seems to me a farmhouse must be burning.

Antonyms:

be,be certain, real, or true,be the fact,exist.