An avocado is a fruit with a thick green skin and mild, creamy flesh. If you've ever eaten guacamole, you've tasted avocado.
It might seem strange that an avocado is a fruit, because it's not sweet. Avocados have to be cut open before you eat them, and the hard pit in the middle needs to be removed. The inside of an avocado is firm but soft, a pale green shade. The word avocado is Spanish, from aguacate, and rooted in a Proto-Aztecan word, *pawa, that also meant avocado.