Simple Definition of illogical
: not showing good judgment : not thinking about things in a reasonable or sensible way : not logical
Examples of illogical
It is illogical to think that things will change on their own.
<the illogical claim that playing basketball makes people taller because one sees so many tall players>
First Known Use of illogical
Seen and Heard
What made you want to look up illogical? Please tell us where you read or heard it (including the quote, if possible).