In HCI we have terms for making novice users happy, such 'easy of use', 'intuitiveness' and systems which feels like they are 'second nature' for the users.

We also have terms for high performance workers such as 'trained' and, well, 'skilled' which implies that they've figured the system out.

But what about the state of a user who has twiddled with a system, been trained and the system then feels 'intuitive' and becomes 'second nature?'

This word would describe a state of the user having feeling of familiarity, but also of mastery.

In order to achieve this, the system needs to reward exploration and learning of the tools and media while at the same time allowing for near-immediate access to basic features.

This is not the same thing as the interface fading into the background and becoming invisible, it is more like the expert craftsman who, while intensely aware of this tools, wields them with the utmost precision and pride. The system encourages and allows the user to become an expert user.

Example. Suppose you are in a conference and during the coffee break you start meeting people. You feel a bit strange as you are not in a familiar environment and also you meet and talk to important people, so you are worrying about the impression you give them. It will take some time before you start feeling comfortable with the people and the environment. After a while though you'll start being yourself and not worry too much about what you say. Similarly, when you are in front of a new computer device (such as a kiosk), you may feel the same way as you would feel in a new environment with strange people. You take some time to observe the system and its various controls, you may be scared a bit in case you will not be able to use it and as a result you might look ridiculous to the people that are queuing behind you. You decide to experiment with some of the controls and after a while you feel more comfortable and you feel you get what you need out of the system.

The Greek Origin. Exikiosis is composed of two Greek words: ex + ikiosis, 'Ex' means 'become' and 'ikiosis' is a noun that stems from the word ikos which means 'home.' Consequently it roughly means become familiar
but it additionally implies that there is a process that leads to this direction.

History of the word. University College London HCI-E Masters student Udy Ravid was having dinner at fellow student's house Frode Hegland. Udy and his girlfriend asked Frode if a term exists in English which describes this state. Udy is from Israel and sometimes pretends his English isn't perfect. Frode didn't have an answer so he called another student, Aspasia Dellaporta (who is, conveniently, both Greek and a genius) and explained the concept to her. She expanded the concept and found a word for it. And now it lives in your head too. Hope you find it useful.

The biggest issue we have found so far is that the word is not too catchy. But you know, it takes time to learn to say: "exi-ki-osis", Exikiosis. Try it. It takes a bit of practice for it to roll of the tongue. It takes a while to get comfortable with and to gain mastery of. Hey, it is what it means.

Another issue we have come across is people are comfortable with expressions of what it means don't see a need for a new word. This I guess, will be a matter of choice.