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: social gathering 
Words: meeting, cinema, club, group, submarine

Answer: submarine


Question: Category: type of sandwich 
Words: grilled cheese, french toast, outing, burger, club

Answer: outing


Question: Category: animals 
Words: stoop, ostrich, geese, pig, duck

Answer:
stoop