Definition
Unlikely event
An unlikely event can happen, but it is less likely to happen than not.
What it means
Unlikely means “possible, but do not expect it most of the time.” Its probability is closer to 0 than to 1 on a simple chance scale. The exact word boundary can depend on the scale a task gives, so check any labels or thresholds shown.
Remember it
Possible, but not the result you would usually expect.
Example
A bag contains 1 star counter and 7 circle counters. Drawing the star is an unlikely event because its probability is 1/8: it can happen, but a circle is much more likely.
Watch for
An event with probability 0 is impossible, not merely unlikely.
Common mix-up
Unlikely does not mean impossible. A small chance is still a chance.
Exact meaning
An unlikely event is a possible event with a low probability, so it is less likely to occur than not occur. On many school probability scales this means a probability greater than 0 and less than 1/2, unless the task defines another threshold.