parasite

Etymology

From Middle French parasite, from Latin parasitus, from Ancient Greek παράσιτος (parásitos, “person who eats at the table of another”), from noun use of adjective meaning "feeding beside", from παρά (pará, “beside”) + σῖτος (sîtos, “food”).

noun

1. (derogatory) A person who lives on other people's efforts or expense and gives little or nothing back.
   A royalist who publicly called for a military intervention to protect the parasite monarchy. 2021-12-01, monamu98, “Thai and Korean netizens oppose debut of H1-Key's Sitala over father's alleged support of dictatorship”, in sportskeeda.com, sportskeeda, retrieved 2021-12-03
   Of all the corrupting effects of wealth there is none worse than this, that it makes the wealthy (and their parasites) think in some way divine, or at least a lovely character of the mind, what is in truth nothing but their power of luxurious living. 1902, Hilaire Belloc, The Path to Rome
2. (derogatory) A sycophant or hanger-on.
3. (biology) An organism that lives on or in another organism of a different species, deriving benefit from living on or in that other organism, while not contributing towards that other organism sufficiently to cover the cost to that other organism.
   It is likely that the long evolutionary trajectory of Mycoplasma went from a reductive autotroph to oxidative heterotroph to a cell-wall–defective degenerate parasite. This evolutionary trajectory assumes the simplicity to complexity route of biogenesis, a point of view that is not universally accepted. 2013-03, Harold J. Morowitz, “The Smallest Cell”, in American Scientist, volume 101, number 2, archived from the original on 2017-01-04, page 83
   Lice, fleas, ticks and mites are widely spread parasites.
4. (literary, poetic) A climbing plant which is supported by a wall, trellis etc.
5. (historical) A retainer or companion of an ancient Celtic warrior, who praised him in song or poetry at gatherings; a bard.
6. (aviation) A component of a composite aircraft which is carried aloft and air-launched by a larger carrier aircraft or mother ship to support the primary mission of the carrier.