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.
--------
Question: Category: personal characteristic 
Words: freezing, calm, positive, cool, popular

Answer: freezing


Question: Category: bird 
Words: goose, hoist, neck, swallow, crane

Answer: hoist


Question: Category: corporate 
Words: solid, sustainability, streamline, firm, private

Answer:
solid