unreliable
adj. B1 Intermediate US //ˌənɹiˈɫaɪəbəɫ// UK //ˌʌnɹɪlˈaɪəbəl// un·re·li·able
adj. not able to be trusted or depended on. If a person or thing is unreliable, they often fail to do what they are supposed to do.
adj. not worthy of trust or confidence; failing to perform consistently or as expected.
The old bus is unreliable and often breaks down.
We cancelled the trip because the weather forecast was unreliable.
Investors grew wary of the company after several quarters of unreliable financial reporting.
From un- + reliable.