Etymology: < classical Latin parasītus (also parasīta , feminine) a person who lives at another's expense < ancient Greek παράσιτος a person who eats at the table of another, a person who lives at another's expense and repays him or her with flattery, a person who dines with a superior officer, a priest who is permitted meals at the public expense < παρα- para- prefix¹ + σῖτος food (see sito- comb. form). Compare French parasite someone who makes it his profession to dine at another's table (1680; also as adjective, ‘living in laziness at the expense of society’ (1817); c1500 in Middle French, in a translation of Terence, in sense ‘table companion of a rich person, who has to entertain him’), also in spec. use in Botany (1721 as adjective in plante parasite; 1764 as noun) and in Zoology (1742 as noun, 1765 as adjective).In sense 2c after French parasite ( I. Geoffroy Saint-Hilaire Hist. générale et particulière des anomalies de l'organisation chez l'homme et les animaux (1836) III. 16). In sense 3 after German Parasit (G. H. O. Volger 1854, in Ann. der Physik u. Chem. 92 72).

Etymology: < parasite n. Compare Middle French parasiter (in isolated attestations, ‘to eat at the common table’ (1567), ‘to live as a parasite’ (1599)), French parasiter to infest as a parasite, to live at the expense of (someone) (both 1910).