having a strong possibility of being unsuccessful

dangerous, risky

depending (on certain things)

dependent

that can be argued about because uncertain

controversial

uncertain; risky

risky

feeling, causing, doubt

questionable, unclear

(of a person) feeling doubt

doubtful

(of a person, behaviours) likely to do unusual or unexpected things

unpredictable; wandering

not likely to be true or to happen

not likely

too great to be calculated

countless, limitless

uncertain; unsafe; depending on chance

tricky, doubtful

(especially of a result or future) doubtful

open to doubt

concerned with speculating

theoretical

made or done as a trial, to test the effect

conditional, experimental

not reliable; not certainly knowing or known

doubtful, changeable

that cannot be counted

incalculable

not yet having made up one's mind

not sure, not definite

not predictable

changeable

not confident; not certain or reliable

doubtful, insecure

varying; changeable; a quantity or thing (e.g. cost, temperature) that can change according to conditions

changing, changeable