1.Epidemic– When a large number of people affected by same infection, the situation is called epidemic. (Noun)
2. Isolation–A state of separation from others and staying alone. (Noun)
3. Lockdown- A situation when people are not allowed to leave or enter a specific area or building for emergency. (Noun)
4. Pandemic- Widely spread over a large part of world or country. (Adjective)
5. quarantine- A specifitime for which a person or an animal is kept in isolation ,may be for the reason of disease. (Noun)
