[mynameisash]

I'm not sure if there's a legal definition, but what I found[0] says that

> Essential services are the services and functions that are absolutely necessary, even during a pandemic. They maintain the health and welfare of the municipality. Without these services, sickness, poverty, violence, and chaos would likely result.

The listed examples of essential services include things not absolutely, positively necessary to protect life and limb:

* Maintenance of communication infrastructure (e.g., telephone system, radio, internet)

* Maintenance of utilities (e.g., gas and electricity)

* Transportation

* Road maintenance/repair

* Banking

* Payroll departments

* Tax collection

[0] https://www.paho.org/disasters/dmdocuments/RespToolKit_24_To...