A lacto-ovo vegetarian (or ovo-lacto vegetarian, and sometimes incorrectly referred to as octo-lacto vegetarian, as "octo" means eight) is a vegetarian who consumes dairy products (i.e. milk and its derivatives, like cheese, butter, or yogurt) and eggs. Lacto means "dairy" and ovo means "eggs". Contrast this with strict vegetarians and vegans who consume neither.
In the Western world lacto-ovo vegetarians are the most common type of vegetarian.