Parasitism (noun)

1. A symbiotic relationship in which one organism, the parasite, benefits at the expense of the other organism, the host.
2. A type of symbiotic relationship in which one organism lives on or within another organism and derives benefits at the host's expense.

Origin:

From greek parasitos ("person who eats at another"s table") + -ism, refers to a relationship between two organisms where one (the parasite) benefits at the expense of the other (the host).

Examples:

1. The tick"s parasitism on the dog"s blood for nourishment is an example of a parasitic relationship.
2. The tapeworm's parasitism in the human gut is a harmful example of a parasitic relationship.
3. The cuckoo"s parasitism of other birds" nests is an example of brood parasitism.
4. The orchid's parasitism on mycorrhizal fungi is an example of myco-heterotrophy.
5. The mistletoe's parasitism on trees is an example of hemiparasitism.