According to Screen Rant entertainment website article X-Men: What Did The 'X' Originally Stand For?, the 'X' in X-Men does not stand for Xavier, but for a condensed form of 'the Extra-Power Men', referring to the extra powers that Professor Xavier bestowed on them.
Also, most of us are aware that Stan Lee first titled the comic "The Mutants," but his editor believed the readership would be unable to understand what or who a mutant was, so Lee recommended X-Men because the main characters possessed "extra" abilities and were led by a man named Professor X.
I've looked through the fandom and other legitimate sources, but there is no explicit explanation regarding the meaning of the X in Professor Xavier's identity, which is my question.