What makes it coffee?

Dictionary.net defines coffee as:

1. The "beans" or "berries" (pyrenes) obtained from the drupes of a small evergreen tree of the genus Coffea, growing in Abyssinia, Arabia, Persia, and other warm regions of Asia and Africa, and also in tropical America. [1913 Webster +PJC]
2. The coffee tree. [1913 Webster]
3. a social gathering at which coffee is served, with optional other foods or refreshments. [PJC]
4. The beverage made by decoction of the roasted and ground berry of the coffee tree. [1913 Webster]
5. a cup of coffee[3], especially one served in a restaurant; as, we each had two donuts and a coffee; three coffees to go. [PJC]
6. also the name of counties in Georgia, Tennessee and Alabama (fun but pointless fact)