In philosophy, nous is the mind's ability to clearly understand what is true. You might think of nous as reason or intellect.
The exact definition of nous varies, depending on whether you're talking to a philosopher, historian, or religious thinker. In Christianity, the nous is the mind, as distinguished from the soul. You can also think of this as the distinction between thinking and feeling. Classic philosophy defines nous as the part of a person's mind that allows them to think rationally and understand. During the 18th century, nous was briefly popular as college slang for "wit or cleverness."