kappaPronunciation: /ˈkapə/Definition of kappa noun the tenth letter of the Greek alphabet (Κ, κ), transliterated as ‘k’. (Kappa) [followed by Latin genitive] Astronomy the tenth star in a constellation:Kappa Orionis [as modifier] Biochemistry denoting one of the two types of light polypeptide chain present in all immunoglobulin molecules (the other being lambda). Origin:Greekkappa in other Oxford dictionaries Definition of kappa in the US English dictionary