parasite
noun
[ ˈparəsʌɪt ]
• an organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other's expense.
• "the parasite attaches itself to the mouths of fishes"
• a person who habitually relies on or exploits others and gives nothing in return.
• "he was a parasite who lived off other people"
Similar:
hanger-on,
leech,
passenger,
drone,
bloodsucker,
sponger,
sponge,
scrounger,
freeloader,
ligger,
cadger,
moocher,
mooch,
bludger,
Origin:
mid 16th century: via Latin from Greek parasitos ‘(person) eating at another's table’, from para- ‘alongside’ + sitos ‘food’.
