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: physical property 
Words: obese, fat, vitamin c, heavy, thin

SOLUTION: vitamin c

PROBLEM: Category: guitar part 
Words: truss rod, fret, neck, bored, strap lock

SOLUTION: bored

PROBLEM: Category: animal 
Words: bird, wave, eagle, fly, ant

SOLUTION:
wave