parasite

/pa.ʁa.zit/
1.
nounmasculine

organism that lives on or in a host and benefits at the host's expense (parasite, e.g. worm, tick)

Le vétérinaire a trouvé un parasite dans l'intestin du chien.

The vet found a parasite in the dog's intestine.

2.
nounmasculine

freeloader; person who lives off or takes advantage of others

C'est un parasite : il vit chez sa sœur et ne contribue à rien.

He's a freeloader: he lives with his sister and doesn't contribute anything.

3.
nounmasculine

electrical/technical interference or noise on a line or signal

On n'entend rien à cause d'un parasite sur la ligne.

We can't hear anything because of interference on the line.