What is the meaning of κ?

the compressibility of a compound

A cardinal number.

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