Undistributed Middle Term

When one part of an argument doesn't properly overlap with another portion of the argument, an undistributed or incorrectly distributed middle term can result.

Example: 

All Bigfoots eat chickens. 

Mr. Spagnolo's favorite food is chicken wings. 

Mr. Spagnolo is a Bigfoot. 

Example: 

Mr. Spagnolo has big ears. 

All dogs have big ears. 

Mr. Spagnolo is a dog.