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.
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Question: Category: temperature 
Words: cold, hot, cool, popular, relaxing

Answer: popular


Question: Category: aesthetic characteristic 
Words: medium, just, light, ghostly, fair

Answer: just


Question: Category: elements 
Words: blaze, water, flame, promote, fire

Answer:
promote