Doubting
Part of speech: verb
Definition: To be undecided about; to lack confidence in; to disbelieve, to question.
Example sentence: There is a lot of rubbish written about toilet humour - people saying it is childish and pretending it is beneath them - but there is no doubting the effectiveness of a really good willy gag.
Distrustful
Part of speech: adjective
Definition: Marked by distrust; doubtful; suspicious.Causing or giving rise to distrust.