TIL. From Wiktionary, looks like people thought it was involved in the formation of acids, so I guess it was "the stuff that made things sour". I knew that oxy = "sharp", but the sour thing is new for me. en.wiktionary.org/wiki/oxygen#...

Yeah, it seems to be a mistake. Acids corrode, and air corrodes (see rust, and other types of, well, oxidation), so oxygen must be the acidic thing (literally, acid-birther). And then translated to all possible languages (Slavic also...)