having a strong possibility of being unsuccessful

dangerous, risky

uncertain; risky

risky

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

unpredictable; wandering

too great to be calculated

countless, limitless

(of a person) without established place in society

dangerous, precarious

(of a person, movements etc) weak; unsteady; unsafe

trembling

that cannot be counted

incalculable

not confident; not certain or reliable

doubtful, insecure

not firm or steady

shaky