unreliable

adjectives

liable to be erroneous or misleading
"an undependable generalization"
is derived from
not worthy of reliance or trust
"in the early 1950s computers were large and expensive and unreliable"; "an undependable assistant"
is derived from
is derived from
antonym
dangerously unstable and unpredictable
"treacherous winding roads"; "an unreliable trestle"
is derived from
lacking a sense of responsibility
is derived from
is derived from
is similar to
showing lack of care for consequences
"behaved like an irresponsible idiot"; "hasty and irresponsible action"