Mother Kos is only ever referred to as “Kos”. However, when Micolash says “Kosm”, he might not be referring to Kos. Throughout the scene, Micolash is actually talking to Oedon, and throughout the game, Oedon also goes by the name of “Cosmos”. And Micolash has been speaking with the Cosmos for a long time—ever since he entered the Nightmare. Micolash was obviously unaware of this, though, evidently thinking he was speaking to Kos, and (possibly due to his insanity) unintentionally combined Kos’ name with the being he was really speaking with; Oedon. The Cosmos. Hence; Kosm. Potentially, this could’ve actually been insighted by Oedon. If they aren’t speaking directly, then Oedon slowly trying to break into Micolash’s mind could’ve resulted in Micolash misunderstanding, hearing not “I’m not Kos, but the Cosmos” but “I’m not Kos, but Kosm”.

Interesting How do you know all this stuff?

I have a writer’s heart, an analytic mind, and a love for Bloodborne. Of course, I’ve read Redgrave’s Paleblood Hunt, and watched various Bloodborne lore analysis, which definitely inspired me, but I also examine the item descriptions, and dialogue, to pull my own conclusions as well.

You think theres hope for Bloodborne 2?