"Amoxicillin" is the International Nonproprietary Name (INN), British Approved Name (BAN), and United States Adopted Name (USAN), while "amoxycillin" is the Australian Approved Name (AAN).
Amoxicillin is one of the semisynthetic penicillins discovered by former pharmaceutical company Beecham Group. The patent for amoxicillin has expired, thus amoxicillin and co-amoxiclav preparations are marketed under various brand names across the world.