TASK DEFINITION: Given a category and a set of five words, find the word from the set that does not belong (i.e. is the least relevant) with the other words in the category. Words are separated by commas.
PROBLEM: Category: emotional status 
Words: ecstatic, excited, content, activity, angry

SOLUTION: activity

PROBLEM: Category: accomodation 
Words: mansion, mountain, flat, house, duplex

SOLUTION: mountain

PROBLEM: Category: window material 
Words: coating, acrylic, plastic, glass, knive

SOLUTION:
knive