Ácsi is the short version of “Állj csak meg!” or simply “Állj meg!” / “Megállj!”,
which can be translated as “Stop!”, “Wait!” or “Wait a second!”.
It’s mostly used when somebody is talking to you and you do not really understand what they are talking about, so you want to stop them and make things clear before going on with the conversation.
It’s said that this expression was born on local parties where gipsy musicians played live music for the people, and when they were playing a song that you didn’t like you simply told them “Ácsi!” to stop them playing and you asked for another song.
Ácsingózni is a verb derived from the word ácsi, and it means “to loiter” (álldogálni) or “to yearn” (sóvárogni / epekedni / vágyódni / áhítozni).