Codex: Chaos Daemons (2018), p46 — The Naming of Daemons

Daemons are chaos incarnate, unfathomable beings of a shifting nature, but there is one constant about each of them, from the lowliest imp to the most towering Greater Daemon: they each conceal a true name. Most such names are a rolling tide of nigh unpronounceable syllables beyond the wit and sanity of most to speak aloud, but to do so is the greatest defence against the unnatural creatures of the warp; to know a Daemon's true name is to hold ultimate power over it, and so their bearers keep them secret, even from each other.

To this end, use-names and titles are utilised instead. These follow certain patterns, although they are recurring themes as opposed to rules. Khorne Daemon use-names are guttural and violent sounding, and those of the Bloodthirsters are often composed of eight syllables or letters, like Khazdrak. Their titles are bold and typically descriptive: the High-handed Slayer, Skullrender, the Unstoppable Fury, and so on. Tzeentch Daemons are most likely to change names and titles, for it often suits their needs to do so; a single Lord of Change might go by many different names and titles at any given time. Nurgle's creations favour names with seven letters, and their epithets are either grandiose or descriptive, such as Feculux the Master Mucanoid. Slaaneshi Daemon use-names utilise sibilant sounds,such as Sslythri or Dryzla, while they have a preference for long, grandiloquent titles such as the Exquisite Matriarch of Agonising Delights.