can someone define dubious 4 me ?

According to the Oxford English Dictionary:

1. Objectively doubtful; fraught with doubt or uncertainty; uncertain, undetermined; indistinct, ambiguous, vague.

b. Of uncertain issue or result.

c. Old Chem. dubious acids: see quot. Obs.

d. Of questionable or suspected character.

2. Subjectively doubtful; wavering or fluctuating in opinion; hesitating; inclined to doubt.

Unsure I would say. For example. If a hobo walked into a fancy hotel the snooty reception guy might say. I am dubious whether or not he will be able to afford a room here

Dubious = doubtful.

Arousing doubt; questionable; open to suspicion; In disbelief; wavering, uncertain, or hesitating in opinion; inclined to doubt; undecided, involves uncertainty or distrust or lack of sureness of an alleged fact, an action, a motive, or a decision