What does DC stand for in ACDC?

Excuse me, could you kindly enlighten me on the meaning behind the abbreviation "DC" as it appears in the term "ACDC"? I understand that it's a popular band, but I'm particularly curious about the specific significance of that acronym within the context of their name. Is it a reference to a certain technical term, a philosophical concept, or perhaps something else entirely? I'd appreciate it if you could shed some light on this matter.