Contrary to known or agreed facts; untrue.
Of or in comparison to a hypothetical state of the world.
A conditional statement in which the conditional clause is false.
A claim, hypothesis, or other belief that is contrary to the facts.
A hypothetical state of the world, used to assess the impact of an action.
Not rational; unfounded or nonsensical.
Of a real number, that cannot be written as the ratio of two integers.
A real number that can not be expressed as the quotient of two integers, an irrational number.