"Well, it basically means something like cosy," I often try, but then immediately feel obliged to crush the hesitant hope I see appear in the eyes of the one who asked, "but not exactly."
It is more than that. It is a credo, a philosophy; it is the battle cry of the people of the Low Countries in the face of unfriendly elements.
Gezellig is bij de haard, by the fireplace, when it's cold and stormy outside, rain ticking the window sill. I remember a story of an old aristocrat with the habit of hiring a homeless person to stand outside his house during the holiday season and to holler "wat is het koud!", my it's cold, just so that it would be more gezellig inside.
Gezellig is een spelletje spelen, to play a board game or a card game and drink een warme choco, a hot cocoa. It is to have a pint or two in your favourite local stamcafé (see previous "Talking Dutch") with your favourite stamgasten, regulars. It is to have Delftware tiles hanging on the wall, emblazoned with devices such as "Zoals het klokje thuis tikt, tikt het nergens". The way the clock ticks at home, it ticks nowhere else.
The word gezellig is derived from gezel, a mediaeval apprentice in one of the guilds who slept in a zaal, a large room, and shared it with others. From zaal to gezel to words like vrijgezel, bachelor, levensgezel, life partner, or gezelschap, company.
It is fair to say, therefore, that gezelligheid needs company. Solitude is its antonym. But, some will argue, the company doesn't always have to be people. It can be your pet, a book or some good music. As long as you're not stuck on a desert island, things can be gezellig.
Granted, it may sound paradoxical - all this wanting to be together - coming from one of the more individualistic necks of the woods. It may even sound a bit fluffy, a bit kitsch at times. But that doesn't seem to matter much to the Flemish. Because in the end, gezelligheid kent geen tijd, time doesn't exist when things are gezellig.