What is the meaning of Κ?

the compressibility of a compound

A cardinal number.

A voiced dorsal click consonant (palatal κ́ = IPA [ɡ͜ǂ]).

Lower-case kappa (κάππα), the tenth letter of the ancient Greek alphabet. It represented the voiceless velar plosive /k/. It is preceded by ι and followed by λ.

The lower case letter kappa (κάππα), the tenth letter of the modern Greek alphabet.

Abbreviation of κύριος (kýrios): Mr

Abbreviation of κυρία (kyría): Mrs, Ms

Source: wiktionary.org