1) Capable of mistakes 2) Errant 3) Erring 4) Error-prone 5) Liable to make error 6) Liable to make mistakes 7) Likely to fail or make errors 8) Not perfect 9) Undependable 10) Unreliable 1) Errant 2) Erring 3) Unreliable 
• (a.) Liable to fail, mistake, or err; liable to deceive or to be deceived; as, all men are fallible; our opinions and hopes are fallible.
Fal'li·ble adjective [ Late Latin fallibilis , from Latin fallere to deceive: confer French faillible . See Fail .] Liable to fail, mistake, or err; liable to deceive or to be deceived; as, all men are fallible ; our opinions and hopes are fallible . 
[adj] - having the attributes of man as opposed to e.g. divine beings 2. [adj] - likely to fail or be inaccurate
frail adjective having the attributes of man as opposed to e.g. divine beings; `I`m only a fallible human`; `frail humanity`
[SAT terms] wanting in moral strength, courage, or will