Civilisation is a mess of a word tbf. Going from civis -> civilis -> civiliser -> civilisation and being a political term the entire time means it carries so much history with it, it couldn't help to be anything other than vague. The Proto-European kewis just meant to settle down, and a civis in Latin was just a settled person (e.g. in contrast to the pastoralist people of what is now Germany). You then get civitas (location of the settled people) as a word for city and then civis narrows to specifically city person in response. As Roman thought developed, civis began to have normative as well as positive associations - for example, what are the duties of a civis, their responsibilities, their rights? And so the word civis now denotes a legal and political status whereby you are afford rights and duties as a civis of Roma/Roman citizen. Non-Romans (by which I mean the city of Rome), even those who were also Italians (as in: lived in the area named Italia), are not extended the civis until the Social Wars, but this gets extended over the centuries so that soon the whole Roman Empire has "city rights", so civis stops being the duties of someone living in the city of Rome and starts being associated with the entire Roman nation/people, so a civis is a person who has particular rights and duties afford to them by their nation (i.e.: citizen).
And so you get notions of civilis, the issues pertaining to civis (i.e., what rights? what duties?), becoming civilis (civiliser) and finally the notion of something having become civilis (civilisation). So we started with something like "settled people/not nomads", and ended up with "people who have established conceptions of what one owes their nation". Only then European refuse to accept conceptions that don't fit their own or recognize that nations don't manifest uniformly and that nation itself is a contested term, and suddenly it ends up with "people who agree with European (or sufficiently similar) conceptions of what one owes their nations", which, unsurprisingly, means only Europe counts as civilised. Funny, that.
So yeah, trash term.
But I am looking forward to Civ 6!