Rare when referred to meat not cooked for very long

According to the online Cambridge dictionary, rare when referred to meat means "not cooked for very long and still red".

As a native speaker of a Romance language I clearly understand the other meaning of rare, that is "uncommon", I'd like to know why rare is also employed to describe a not cooked for long piece of meat…

Solution 1:

“Rare” (meaning “uncommon”) and “rare” (meaning “undercooked”) are actually two different words that nowadays happen to have the same spelling and pronunciation. The first “rare” 1 stems from Latin “rarus” and has cognates in most Romance languages. The second “rare” 2 is of Germanic origin, and used to be written “rere”, “rear” etc in the (distant) past.