From Wikipedia Gemütlichkeit

The underlying concept is that social tensions and certain environments can cause stress, resulting in a feeling of alienation. Gemütlichkeit is an active way of preventing such negative influences by going to places and/or meeting with people that are regarded to be gemütlich. A gemütlich person again is one that takes part in this lifestyle and knows about the tensions he/she is able to cause, and thus tries to avoid these things actively. This way an agreement is established to make an “environmentally cosy” site (Heuriger, garden, cellar, backyard restaurant, living room…) “socially cosy”.

One characteristic of a gemütlich situation is that one could blot out everything else (past, future, other places and absent people) and yet everything would be fine (an eternal “now and here”). Germans describe that as “leaving everything at the doorstep” (though a gemütlich place doesn’t necessarily have to be inside a house).

A similar word, gezelligheid (/ɣəzɛləɣhæɪt/), exists in Dutch. The Dutch gezelligheid however is always attached to a social situation (a gezellige person is somebody who likes to be among people and socializes well), whereas Gemütlichkeit can also be enjoyed alone.

There is also a Danish equivalent (hygge), which basically means the same.

In Russian, the word commonly translated as cosiness, уют [uˈjut], carries almost identical connotations as the German word.

In Czech, ‘pohoda’ means cozy, ease, tranquility and well-being. A group of people may have ‘pohoda’ together.