I'm hearing the current measures taken during the current coronavirus pandemic referred to in the media as "curfews". To me the word "curfew" implies that people are required to behave a certain way during certain hours of the day. The definitions I've seen given tend to agree with my instinct. In other words, requiring people to be off the streets and in their homes after 6 pm or before 8 am sounds like a curfew to me, but a constant lockdown or what some are calling "shelter in place" doesn't.
n.
1. A regulation or rule requiring certain or all people to leave the streets or be at home at a prescribed hour.
2.
a. The time at which such a restriction begins or is in effect: a 10 pm curfew for all residents.
b. The signal, such as a bell, announcing the beginning of this restriction.
American Heritage Dictionaryn.
1. an order establishing a time in the evening after which certain regulations apply, esp. that no unauthorized persons may be outdoors or that places of public assembly must be closed.
2. a regulation requiring a person to be home at a stated time, as one imposed by a parent on a child.
3. the time at which a daily curfew starts.
Random House Kernerman Webster's Dicitonary2a : a regulation enjoining the withdrawal of usually specified persons (such as juveniles or military personnel) from the streets or the closing of business establishments or places of assembly at a stated hour The city ordered a curfew to prevent further rioting.
b : a requirement that someone (typically a child) be home by a particular time Instead, [parents] should make a point of enforcing curfews and standards of behavior that reflect their family's values …— Pam Carroll
Merriam-Webster Dictionary1A regulation requiring people to remain indoors between specified hours, typically at night. ‘a dusk-to-dawn curfew’
Oxford dictionaries (at lexico.comA curfew is an order specifying a time during which certain regulations apply.1 Typically it refers to the time when individuals are required to return to and stay in their homes.
Curfew (Wikipedia)
However it's possible that the Collins Dictionary definitions describes the current public health measures, as it doesn't seem to require a time component:
n
1. (Government, Politics & Diplomacy) an official regulation setting restrictions on movement, esp after a specific time at night
2. the time set as a deadline by such a regulation
Collins Dictionary
Edit: India has recently ordered people to stay off the streets between 7 am and 9 pm. Some people consider a curfew to specifically restrict movement after dark, but to me this sounds like a curfew. I guess you could describe it as a reverse curfew as people are only allowed out at night.