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.

Category: chocolate food 
Words: cake, fudge, rich, invent, cream
invent

Category: social gathering 
Words: place, bar, doorstep, club, outing
doorstep

Category: weather 
Words: tangle, sunny, brisk, size, fair

size