parasite
/ˈpærəsaɪt; `pærəˌsaɪt/ n
1 animal (eg a flea, louse) or plant (eg mistletoe) that lives on or in another and gets its food from it 寄生物（如寄生虫或寄生植物）.
2 (derog 贬) person who lives off others and gives nothing in return 靠他人为生的人
live as a parasite on society 像寄生虫似的靠社会为生.