untrustful, un-trust′fool, adj. not trusting: not trustworthy.
Unwatchful trust is a delusion, and untrustful watching is in vain.
He took the letter from Mr. Pyecroft's unwilling and untrustful hands and glanced it through.
1570s, "trustworthy," from trust (n.) + -ful. Meaning "trusting" attested from 1832. Related: Trustfulness.