* In Greek letters: Kappa (Κ, κ) is simply the tenth letter of the Greek alphabet. It doesn't have a further expansion.
* In online slang: Kappa (often stylized as Kappa) is an emoticon used on Twitch and other online platforms to indicate irony, sarcasm, or a joke. It doesn't stand for anything specific.
* In other contexts: There might be niche uses or abbreviations where "Kappa" represents something specific, but those would be context-dependent and require further information.