Contronym
A word that can mean one thing while also meaning the complete opposite is referred to as a contronym. It can be thought of as an antonym to itself. Cleave, for instance, can mean either to cling to something or to sever it. Additionally, the phrase “in the first degree” can refer to a very serious crime, such as “murder in the first degree.” But you can also use it to imply that something is not nearly as bad as it seems, such as a burn of the first degree, which is not as severe.