zelje

1. leafy greens
   Baka je napravila pitu sa zeljem. — Grandma made a pie with greens.
   Na pijaci je već stiglo prolećno zelje. — Spring greens have already arrived at the market.
2. (plant) edible dock, especially patience dock
   Kupila sam vezu zelja za zeljanicu. — I bought a bunch of dock for a greens pie.

In Serbia cabbage is kupus; zelje usually means leafy greens for pies, most often dock (hence zeljanica). The meaning "cabbage" is Croatian, and "spinach" is Bosnian.