English▸ noun a state, period, or place of isolation in which people or animals that have arrived from elsewhere or been exposed to infectious or contagious disease are placed:
many animals die in quarantine.
▸ verb [with object] impose isolation on (a person, animal, or place); put in quarantine:
I quarantine all new fish for one month
they had to quarantine infected households.
– ORIGIN mid 17th century : from Italian quarantina ‘forty days’, from quaranta ‘forty’.