PARASITE

n. organism which lives on or inside another organism; organism that obtains its livelihood at the expense of another creature

Parasite! is the second EP by Swedish heavy metal band Mustasch. It was released in 2006.
See more at Wikipedia.org...

Parasitism is one version of symbiosis ("living together"), a phenomenon in which two organisms which are phylogenetically unrelated co-exist over a prolonged period of time, usually the lifetime of one of the individuals. The requirement for a prolonged interaction precludes predatory or episodic interactions (such as a mosquito feeding on a host), which are usually not seen as symbiotic relationships. Symbiosis encompasses commensalism ("eating at the same table", wherein two organisms co-exist in the same space, and one organism benefits while neither harming nor helping the other), through mutualism (wherein both species benefit from the interaction) to parasitism, wherein one organism, usually physically smaller of the two (the parasite) benefits and the other (the host) is harmed. (Various forms of "social parasitism", kleptoparasitism, and "cheating parasitism", as discussed below, are characterized by a less close association between a parasite and a host, however.) Especially in the field of medical parasitology, the term "parasite" has come to mean a eukaryotic, pathogenic organism. Thus, protozoan and metazoan infectious agents are classified as parasites while bacteria and viruses are not. Interestingly, fungi are not discussed in textbooks of medical parasitology, even though they are eukaryotic.
See more at Wikipedia.org...

Noun
1. an animal or plant that lives in or on a host (another animal or plant); the parasite obtains nourishment from the host without benefiting or killing the host
(antonym) host
(hypernym) organism, being
(hyponym) endoparasite, entoparasite, entozoan, entozoon, endozoan
(classification) plant, flora, plant life
2. a follower who hangs around a host (without benefit to the host) in hope of gain or advantage
(synonym) leech, sponge, sponger
(hypernym) follower

adj. parasitical, living on or inside another organism; obtaining its livelihood from another creature

n. parasite, organism which lives on or inside another organism; organism that obtains its livelihood at the expense of another creature

v. parasitize, live as parasite

v. parasitize, infect with parasites