Etymology

"The origin of the word cheese appears to be the Latin caseus, from which the modern word casein is closely derived. The earliest source is probably from the proto-Indo-European root *kwat-, which means "to ferment, become sour".

In the English language, the modern word cheese comes from chese (in Middle English) and cīese or cēse (in Old English). Similar words are shared by other West Germanic languages — Frisian tsiis, Dutch kaas, German Käse, Old High German chāsi — all of which probably come from the reconstructed West-Germanic root *kasjus, which in turn is an early borrowing from Latin.

The Latin word caseus is also the source from which are derived the Spanish queso, Portuguese queijo, Malay/Indonesian Language keju (a borrowing from the Portuguese word queijo), Romanian caş and Italian cacio.

The Celtic root which gives the Irish cáis and the Welsh caws are also related.

When the Romans began to make hard cheeses for their legionaries' supplies, a new word started to be used: formaticum, from caseus formatus, or "molded cheese". It is from this word that we get the French fromage, Italian formaggio, Catalan formatge, Breton fourmaj and Provençal furmo. Cheese itself is occasionally employed in a sense that means "molded" or "formed". Head cheese uses the word in this sense."
~ according to Wikipedia