QUESTION: What does "offline" mean?
1. It means to use the printer not through the Internet.
2. It's off line if it (the printer) is switched off - the internet is irrelevant
The final word -
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Definitions
In computer technology and telecommunication, online and offline are defined by Federal Standard 1037C.[citation needed] They are states or conditions of a "device or equipment" or of a "functional unit". To be considered online, one of the following may apply to a system: it is under the direct control of another device; it is under the direct control of the system with which it is associated; or it is available for immediate use on demand by the system without human intervention.[citation needed]
In contrast, a device that is offline meets none of these criteria (e.g., its main power source is disconnected or turned off, or it is off-power).
The Oxford dictionary defines "online" (sometimes also referenced as "On the Line") as "controlled by or connected to a computer" and as an activity or service which is "available on or performed using the Internet or other computer network".[1] The term is utilized within terms such as these: "online identity", "online predator", "online gambling", "online shopping", "online banking", and "online learning". The online context is given to other words by the prefixes "cyber" and "e", as in the words "cyberspace", "cybercrime", "email", and "ecommerce".[2]
https://en.wikipedia.org/wiki/Online_and_offline
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My own opinion is that offline and online is just computer jargon for the plain English words "unavailable" and "available"
without any necessary reference to the internet or how about just plain old off or on.
If you doubt this just try printing something to a printer that is turned off and the printer driver will report that the printer is "offline" even though you may be also surfing the internet at the same time trying to print to printer that is turned off.