What does "cyber-" actually mean?

I'm heading into the postgraduate phase of my Computer Science-oriented studies, and I can't put my finger on what this root means.

According to Etymology Online it comes from Cybernetics, which in turn comes from the greek for "Helmsman" and is the study of governation or governing systems.

But modern usage, such as cyberspace, cybercafe, cyberattack, cyberterrorism, cybermosque, cybersex, cyberbullying, and such seem to use it synonymously with "Internet"

Of course, you could argue that you use a cybercafe to interact with a primitive virtual governor, a cyberspace is a place where a lot of virtual governors "reside", while cyberattacks try to disrupt these governors.

But cyberbullying and "cybering" really don't fit into that scheme, unless you were to day that cyberbullying is "bullying by relaying domineering or intimidating messages with the help of a governor." but then again "physics" could be a governor. You shout mean things into the air and physics makes sure your overbearing soundwaves propagate to your target.

Bo that would mean that pretty much everything is cyber-, because everything is controlled by something.

The rational middle ground would be for "cyber-" to now mean "internet," unless it is followed by a greek or latin root, in which case it would mean "control systems"

Is it safe to assume this?

First off, attack, terrorism and sex all have Latin roots, so your proposed rule of thumb doesn't even work on your own examples.

The closest hypernym for all the newer things cyber is probably "virtual". But not necessarily Internet-related. Any LAN can be a cyberspace. (And some might even consider a single app or game a cyberspace.)

Cybernetics and cybernetic are the odd ones out, or rather the hinge point, as they cover various meanings each. Coincidentally, that nicely demonstrates that you can't arrive at the meaning simply by looking at the word. So any rule of thumb will fail.

Cybernetics is the exact same word in any context, and it is only from that context that you can tell if it means "the theory/science of communication and control in the animal and the machine", "the art/study of governing, controlling automatic processes and communication", or "technology related to computers and Internet".

Words can have more than one meaning, and so can morphemes. If we use a morpheme to mean "dog" in one word but "truck" in another, then there simply is no middle ground. Looking at the etymology at that point is at best useless, and at worst an etymological fallacy. If you don't like my invented example and think it is an exaggeration, try and find a hypernym for "door", "passageway", and "scandal", which are only some of the meanings -gate- can have.

Likewise, -cyber- can be as flexible as we choose to make it. Cybernetics can mean whatever it means regardless of what cybercafé happens to mean. And a cyborg can sit on the subway next to a cyberterrorist, but that's about as much as they have in common. Just like nobody is offended that the woman and the wife sitting opposite them are no longer related.

The meaning has been broadened through popular use and, in so doing, it has become diluted by people who either don't apply it properly, or seek to draw parallels which get mistaken for genuine associations as time passes. That's what popular culture does - I wince whenever I hear or read news about "hacking" which invariably demonstrates a complete lack of insight into what was perpetrated.

My degree was in Biomedical Engineering and Cybernetics. The etymology of cybyernetics has already correctly been given here as κυβερνητικός (kubernētikós), the Greek sailor exerting control over his environment, and that is the true meaning of the field. It is about intelligent systems of control, nothing more, and the essence of this is a very simple concept: feedback. Like the Greek sailor, it is not enough to exert force to achieve will - the results of the exertion must be perceived, and compared with the desired outcome. If the sailor finds he is veering to the right due to winds or currents, he must apply change using the rudder in order to maintain his course. Thus his actions in this instant are predicated on the results of his actions in the preceding instant(s); what is happening influences what will happen next.

Taking an example of technology, consider climate control within a building. Once the thermostat has been set, the system has been given its desired outcome: say 26 degrees Centigrade. If a room's temperature exceeds this, then the air conditioning will be triggered and the room will be actively cooled, until the point at which the desired temperature is reached, when the system will cease running the aircon. Conversely if the room is too cool, heating will be engaged in the same manner. We're all familiar with this form of feedback, and any system which incorporates it may be thought of as cybernetic, although it is generally only applied to systems created by humans.

The reason cyber has been applied so universally to mean all things internet-enabled is not because of the internet itself, but because of the properties of this system. I can say something to my friend while he is standing next to me, or I can write my message down on a piece of paper and show it to him - the outcome is the same (leaving out the lack of body language/intonation which is a subject for another discussion). The outcome remains the same if I type it on an electronic device, and show him the screen. It still remains the same if I type it on an electronic device and it appears on the screen of his electronic device - but now, the properties of the conversation have altered. The same message is conveyed, but (i) I no longer need to be next to him, so long as we are connected to the same infrastructure, and (ii) I don't have to be giving my message at the same time as he is able to receive it. Our communication paradigm has been decoupled in both space (we are telecommunicating, from the Greek τῆλε meaning afar, far away) and time (we are communicating asynchronously, from the Greek σύν (sún, “with”) + χρόνος (khrónos, “time”), negated with a).

However, this decoupling is not to be confused with cybernetics. If we ignore all of the cybernetic systems that facilitate the actual internet, as parts of the infrastructure, then it becomes clear that use of the internet as a medium does not constitute a cybernetic system in itself. The outcome of me delivering a message and my audience receiving it is the same, whether I am standing on a podium in front of them or posting it on my Facebook page. The internet simply becomes a tool, a mechanism used to perform this action remotely and asynchronously; the fact that it utilises cybernetic principles does not make any system that involves it inherently cybernetic per se. If I follow someone down the road and hurl abuse at them, I am bullying. If I do it on Facebook, I am bullying. The fact that I did so using a different medium does not change the outcome, and words like "cyberbullying" are part of the reason why our legal system has been so insufficient and outmoded in tackling all of the issues that are arising from an internet-enabled world, such as online abuse and so-called piracy.

TL;DR: words like cyberspace, cybercafe and cyberterrorism all refer to the same thing as their real-world counterparts, which are taking place by leveraging (usually internet) technology. The conflation of this medium with the basic action itself does not alter the meaning of the word. In this context cyber, by itself, has no inherent meaning, in the same way that "app" is short for "application" and nothing more.

This is what etymology says to help us understand the meaning of cyber

cyber: as an element in word formation, ultimately from cybernetics (q.v.). It enjoyed explosive use with the rise of the Internet early 1990s. One researcher (Nagel) counted 104 words formed from it by 1994. Cyberpunk (by 1986) and cyberspace were among the earliest. Cyber is such a perfect prefix. Because nobody has any idea what it means, it can be grafted onto any old word to make it seem new, cool -- and therefore strange, spooky. ["New York" magazine, Dec. 23, 1996] As a stand-alone, it is attested by 1998 as short for cybersex (which is attested by 1995).

Cybernatics(n.) coined 1948 by U.S. mathematician Norbert Wiener (1894-1964) from Greek kybernetes "steersman" (metaphorically "guide, governor") + -ics; perhaps based on 1830s French cybernétique "the art of governing." The future offers very little hope for those who expect that our new mechanical slaves will offer us a world in which we may rest from thinking. Help us they may, but at the cost of supreme demands upon our honesty and our intelligence. [Norbert Weiner, "God and Golem, Inc.," 1964]

The term 'cyberspace' was coined by William Gibson in his 1986 short sci-fi story "Burning Chrome". He chose it after some deliberation, as a cool-sounding phrase to describe the domain of connected computers, which he visualised very differently - "a mass consensual hallucination" in computer networks.

The fact the the word is pretty inappropriate (one could hardly describe the internet as 'control-space'!) was neither here not there to Gibson, he just wanted a catchy way to describe a literary entity. He did so very well, and the name has stuck.

BTW I highly recommend Burning Chrome, or indeed any of Gibson's work, the Sprawl trilogy especially (Neuromancer, Count Zero, Mon Lisa Overdrive) (which were an inspiration for the Matrix films, with Mona Lisa Overdrive being the name of a track from the Matrix Reloaded)