Contronyms are words that are their own antonymns.

out means visible (the stars are out early tonight)
out means invisible (the street lights are out in this part of town)

oversight means an error (the misspelling was an oversight)
oversight means care (he was given oversight of the child)

rent means to pay for the use of something (she needs to rent a car)
rent means to sell the use of something (the dealer will rent him a car)