unreliable (
http://definr.com/unreliable)
adj 1: liable to be erroneous or misleading; "an undependable
generalization" [syn:
undependable]
2: not to be trusted [syn:
undependable]
3: not worthy of reliance or trust; "in the early 1950s
computers were large and expensive and unreliable"; "an
undependable assistant" [syn:
undependable] [ant:
reliable,
reliable]
4: dangerously unstable and unpredictable; "treacherous winding
roads"; "an unreliable trestle" [syn:
treacherous]
5: lacking a sense of responsibility