unreliable

/ənriˈlaɪəbəl/

/ənrɪˈlaɪəbəl/

Someone unreliable can't be trusted to do something. Things can be unreliable too, like a bike with a wobbly wheel.

The word "rely" is a clue to what unreliable means. When you can rely on something, you can count in it — it's reliable. On the other hand, you'd better not count on an unreliable person. People can be unreliable because they're dishonest, always late, bad at their job, or just inconsistent. Things can be unreliable because they're broken or old. A train schedule can be unreliable if the trains are never on time. Unfortunately, there's a lot of stuff in life that's unreliable, so be careful.

Definitions of unreliable

1. adjective

   not worthy of reliance or trust
   “in the early 1950s computers were large and expensive and unreliable”

   synonyms: undependable

   erratic, temperamental, wayward

   likely to perform unpredictably

   uncertain

   not consistent or dependable

   unsound

   of e.g. advice

   untrustworthy, untrusty

   not worthy of trust or belief

   antonyms:

   reliable

   worthy of reliance or trust

   certain, sure

   reliable in operation or effect

   tested, time-tested, tried, tried and true

   tested and proved to be reliable

   undeviating

   used of values and principles; not subject to change; steady

   trustworthy, trusty

   worthy of trust or belief
2. adjective

   liable to be erroneous or misleading
   synonyms: undependable

   fallible

   likely to fail or make errors
3. adjective

   dangerously unstable and unpredictable
   “an unreliable trestle”

   synonyms: treacherous

   dangerous, unsafe

   involving or causing danger or risk; liable to hurt or harm
4. adjective

   lacking a sense of responsibility
   synonyms:

   irresponsible

   showing lack of care for consequences