'Civilization' and 'civilized' are two words that I often use, without defining exactly what they mean. This is because the two concepts are very broad; there are a lot of things that go into making, defining, and characterizing a civilization.
For example, one of the best indicators of civilization, both in history and among current countries, is indoor plumbing. Any group of people that does not or cannot maintain a plumbing system for most of its populace does not deserve to call itself a civilization.
But this does not mean that we can improve our civilization by training more plumbers or building more plumbing. Plumbing is a symptom, not a cause, of civilization. One of the biggest and most important questions for humanity is what causes a good civilization.
I have often connected science, rational thinking, and the scientific method with civilization. That was somewhat sloppy. Science is kind of like plumbing in that it is a symptom of civilization. While science and engineering make civilizations stronger and more powerful, and dramatically improve everyone's quality of life, they are not what most people intuitively connect with the word 'civilized'. As Hitler and Stalin showed us, it is possible to combine science and technology with barbarity and savagery. And it is possible to imagine an enlightened and civilized group of people who do not possess much technology.
Some people connect manners and politeness with civilization. I believe that this is folly. An extremely complicated system of etiquette and protocol is usually a sign that something has gone horribly wrong with a group of people. It signifies that they are afraid to speak honestly and that they have nothing better to do with their time than to invent and follow pointless rules.
I believe that the core definition of 'civilized' is 'having respect for the rights of other people' and that the core definition of 'civilization' is 'a society where everyone's rights are respected'. Civilized people respect the rights of life and liberty above all else, and they design their social rules and institutions so that these rights are sacred above anything else. Civilized people respect property rights, and this generates conditions that foster economic activity that makes the society richer. Civilized people respect the rights of honest debate and intellectual inquiry, and this generates conditions that allow science and technology to thrive.
Scientific freedom in combination with economic freedom is what created all the marvels of civilization that we enjoy today. If you lose either, your civilization cannot advance. But if your society fails to respect and guarantee the fundamental rights of human beings, it will either fall to pieces or become a plague upon humanity.