(of trees) losing their leaves annually (especially in autumn)

not around for long

(of a person) feeling doubt

doubtful

not solidly built; not enough

weak, imaginary

(especially) (doing things, done) without a proper sense of responsibility

careless, reckless

not to be trusted

deceitful, untrustworthy

lasting for a short time only

temporary

false or disloyal (to a friend, cause etc); dangerous, severe

dishonest, disloyal

not ethical

dishonest, immoral

that cannot be relied on; not to be trusted

not trustworthy, not true

not confident; not certain or reliable

doubtful, insecure

not trustworthy

not dependable, unfaithful

a poor person having no fixed home

unsettled; vagrant