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: construction 
Words: digger, concrete pourer, crane, derrick, excavator

Answer: derrick


Question: Category: window material 
Words: glass, coating, panel, spatula, lead

Answer: spatula


Question: Category: boats 
Words: blind, hull, lifeline, crew, deck

Answer:
blind