Absurd
Part of speech: adjective
Definition: Contrary to reason or propriety; obviously and flatly opposed to manifest truth; inconsistent with the plain dictates of common sense; logically contradictory; nonsensical; ridiculous.
Part of speech: noun
Definition: An absurdity. — Alexander Pope (with the) That which is absurd.
Example sentence: There is nothing so absurd that some philosopher has not already said it.
Unlogical
Part of speech: adjective
Definition: Not logical; illogical