What does the Greek word “kefi” mean?

What my peers said. Being upbeat and in a good mood, having fun. To do something with kefi means you’re smiling, you’re doing it with gusto, you’re having fun. To have kefi is to be in a good mood.

Kefi is one of those Greek words that is routinely listed as “untranslatable”, because it has such deeply embedded cultural resonance. Like most of those words, it is a loan from Turkish. And at least in this instance (unlike say merak “hypochondria” > meraki “yearning; diligence in craftmanship”), the meaning in Turkish seems pretty close.