Amazingly, the engrbian language doesn't spell this as weekendica, or weekenditsa or weekendizia or anything of the like. This word is older than it, from the times when "weekend" was incorporated into the language by the old, phonetic rules, as "vikend".
Vikendica is a little house with a garden, vineyard and/or orchard, slightly out of town but not too far, where you'd go to spend your weekends, and perhaps have a party (i.e. get drunk like swine) with your inner gang, far from prying eyes. It would usually be near the river, like the whole colony of those that sprouted in Grocka in the sixties, mostly facing Danube.
It was a passtime of the middle class in SFRY. Managers, intellectuals, well-off workers who wanted to make a buck or two on the side, or grow their own food, or fruit for the moonshine and winter preserves, or just wanted to get away from seeing the same boring faces for eight hours every day. Except that they were hit by the paradox - those boring faces would buy nearby lots, build their own and then they'd be neighbors, too.
The house could be any size - from some single-room cottage with just one bed and space for tools, to a two-storey building. Sewage systems, fences, gates, water, electricity, phone and road were wildly optional, in differnt places and times. For sewage, they'd mostly dig their own cesspools once they installed a bathroom; if not, then they'd simply put together an outhouse some meters away from the house. Electricity would come later, years later. Fences - chain-link on the sides, sometimes brick and grille facing the road, with an iron gate, or none at all. Water - most have their own wells, with hand pump; many have installed internal electric pump and plumbing (once they got electricity). Phone is rare, and most of these places are now covered with mobile so nobody cares about wiring. Road is usually nearby, if not all the way to the gate. Actually, having no road makes it rather unfeasible to maintain, so almost all of them are within 200m to the nearest.
These were supposed to be vacant most of the year - the very name implies they'd be used on weekends and holidays - but the times have changed. Very few new ones are built now, no new places with them have came into being in the last decade or two. But they are now more densely populated, as the original owners and builders are probably dead, and most of these were resold several times; the new owners generally try to get more produce out of them and use them less for partying. They now mostly buy it when retirement is on the horizon, to stay active and to have something to do, and to help their budget. There are also cases when they simply move to live there, leaving their place in the city to their kids, who otherwise wouldn't have much chance of making their own place.