Definition of: parasite

(par′ə·sīt) noun
1. Biol. An animal or a plant that lives on or in another organism at whose expense it obtains nourishment and shelter.
2. An obsequious sycophant who lives at another's expense.
3. In ancient Greece and Rome, one who secured a welcome at the tables of the rich by means of fawning and flattery. [<L parasitus <Gk. parasitos, lit., one who eats at another's table <para- beside + sitos food]
—par′a·sit′ic (-sit′ik) or ·i·cal adjective
—par′a·sit′i·cal·ly adverb