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: mode of transportation 
Words: beetle, fly, soar, bus, car
beetle

Category: corporate 
Words: solid, sustainability, streamline, firm, private
solid

Category: social gathering 
Words: cinema, club, french toast, picnic, community

french toast