So there was this word, orkhestra, in Ancient Greek. Latin borrowed it thence as orchestra, English borrowed it from Latin as orchestra, and then Japanese borrowed it from English, predictably, as okesutora. Then the Japanese added kara -- empty -- and created karaokesutora, empty orchestra, which they then condensed/shortened into karaoke. Then English borrowed from Japanese this new word, karaoke. Italian (derived from Latin) and Modern Greek (derived from Ancient Greek) borrowed it from English and got their own karaoke.
Etymology is strange.