I like this word. In other Slavic languages it signifies a downward movement, the going down of something. Mostly referring to the sunset or with association: the West.
That would be "západ" in Czech. :) And yes, there are jokes based on these differences. There's a sentence in Polish that to a Czech person sounds like "I'm f--ing drugs on the toilet." while it actually means "I'm looking for a way/path to the West."
So that would be "Szukam drogi na zachód". ;-) I can understand the confusion. Already in the Polish course we were warned for the false Czech friend of 'szukac'. :-)
Another of my favorite Polish sentences is "Na zachodzie bardzo wielkie wiatry". While in Poland it forecasts windy weather in the western part of the country, in Czech it sounds like one had a lot of beans for dinner and it gets quite windy in their bathroom as a consequence.
Well, it HAS something to do with a downward movement, the going down of something.
why ... I d say it is a kalk from chodit AND za which can translate as to hide, go behind ... In old Czech there was reterát (WC) which reminds of a retreat .. this movement behind into quiet place again