What say the three little brown books about it? Very few things, but as always, very interesting. The authors, Gygax and Arneson, simply, as they say, provide guidelines. Cryptic guidelines that the reader must decode to soak up the spirit of the original rules. Well, some quotations now :
"Before the game begins it is not only necessary to select a role, but it is also necessary to determine what stance the character will take - Law, Netrality, or Chaos. [...] One can attempt to communicate through the common tongue, language particular to a creature class, or one of the divisional languages (law, etc.). [...] Monsters can be lured into service if they are of the same basic alignment as the player-character ..."Two words stand out from the crowd : stance and divisional. A stance is "the attitude of a person or organization towards something; a standpoint" (Oxford Dictionary). So alignment is the attitude of the character/monster towards something (what ?). It's NOT a trait, a way of behaving or something like that. This is closer to a political opinion.
-Gygax & Arneson, OD&D : Men & Magic (emphasis added).
"Divisional" is also very informative : a division is (inter alia) "one of the parts, sections, or groups into which something is divided", "an administrative and tactical military unit that is smaller than a corps but is self-contained and equipped for prolonged combat activity" or "a splitting into factions; disunion" (Oxford Dictionary). So, alignment (interpreted by the book) is a military division into several factions resulting from "political views" (intrinsic or not). Here we are back to the days of wargaming (Chainmail, Arneson's First Fantasy Campain and its army list depending on alignment) : races supporting militarily one of the fighting factions (men and several other peoples are divided on this). Think of a civil war or better : think of Ragnaroth.
The Threefold Apocalyptic Alignment. Choose your side : the Asgardian gods, the Great Old Ones or the Wildness !
Wait... you said Great Old Ones ?
"Alignment on the planet of Carcosa is defined solely by one’s stance towards the Great Old Ones. Nothing else is considered. All behaviors, including the most noble and altruistic as well as the most vile and despicable, are found amongst all three alignments. Similarity of alignments does not necessarily indicate friendship, and opposite alignments does not necessarily indicate enmity. For example, nothing is unusual in a lawful man and a chaotic man joining forces to defeat a lawful foe."Yes... it's a stance. Choose your side and drop these prohibitions and these forced behaviors.
-Geoffrey MacKinney, Supplement V : Carcosa (emphasis added).
Choose OD&D !