You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
Given a set of four words, generate the category that the words belong to. Words are separated by commas. The possible categories are social gathering, accomodation, physical property, measurement unit, corporate, nutritional value, boats, police punishment, location (proximity), card games, outdoor sport activity, military rank, baby animals, weather, consumer product, animals, boxing terminology, food, chocolate food, bird, type of sandwich, date status, body part, ocean, employment activity, moral characteristic, elements, poker, computers, construction, guitar part, shady activities, physical activity, kitchenware, temperature, type of rigidity, emotional status, season, mode of transportation, window material, activity, emotional display, geographical property, fried food, store status, widespread, aesthetic characteristic, alcoholic drinks, secretary duty, direction, personal characteristic, and animal.

excavator, crane, hoist, upraise
Solution: construction
Why? These four words are all construction equipment, such as 'excavator', 'crane', and 'hoist', or describe a common activity used in construction, such as 'upraise'.

New input: below, ground, opposite of up, down
Solution:
direction