noun

1. a person, as in ancient Greece, who flattered and amused the host in return for free meals
2. a person who lives at the expense of another or others without making any useful contribution or return; hanger-on
3. Biol. a plant or animal that lives on or in an organism of another species from which it derives sustenance or protection without benefit to, and usually with harmful effects on, the host

Etymology: L parasitus < Gr parasitos, one who eats at the table of another, parasite, toady < para-, beside (see para-) + sitos, food, grain