parasitic
adj.living on or inside another living thing and taking food from it. It also describes people or things that take advantage of others without giving anything back.
adj.relating to or characteristic of an organism that lives in or on another organism and benefits by deriving nutrients at the host's expense. Often used figuratively to describe social or economic relationships where one party exploits another.
“The parasitic plant grows on the branches of large trees.”
“Biologists studied the parasitic relationship between the wasps and the local caterpillar population.”
Typically used attributively before a noun; in technical contexts, it describes unwanted energy loss in electronic circuits.
“The researchers explored the phenomenon in a series of laboratory experiments in which they exposed blue mussels to larvae from three different species of parasitic flatworm.”
“The parasitic fungi in the Cordyceps genus are a favorite subject of nature documentaries.”
From parasite + -ic.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.