Definitions:

1. Describes something or someone that cannot be depended upon, often due to inconsistency or a lack of reliability. ADJECTIVE
   • After several broken promises, he proved to be an untrusty friend.
2. Unreliable or not worthy of trust. ADJECTIVE
   • The untrusty nature of the old bridge made crossing it a dangerous endeavor.

Synonyms:

• dubious
• questionable
• undependable
• unreliable
• unsure
• untrustworthy