If you know the definition of this noun by quick insight without relying on reason, you know what intuition means!
Intuition is a noun whose definition means that someone uses quick understanding to interpret but without using reasoning or perception, a snap judgment. The definition of the word comes from the Latin roots in- meaning "at" or "on" and tueri meaning "look at, watch over." A relative of intuition is tuition, and even though we don't use this particular meaning anymore, it used to refer to having guardianship or custody. If we use our intuition it means that we don't always make the correct interpretation, and in fact, the Australian writer Christina Stead wrote, "Intuition is not infallible; it only seems to be the truth."