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: geographical property 
Words: horizontal, hotel, flat, lined, smooth
hotel

Category: mode of transportation 
Words: dive, fly, soar, jog, wave
dive

Category: bird 
Words: swift, derrick, crane, heron, tackle

tackle