The term 'mercantile marine' refers to all commercial ships owned by a country or its citizens. There are several synonyms for the term including 'merchant navy', 'commercial shipping fleet', and 'merchant marine'. 'Merchant navy' is commonly used in countries such as the United Kingdom, while 'merchant marine' is the preferred term in the United States. Other synonyms for mercantile marine include 'trading ships' and 'cargo ships'. These terms all refer to the same concept of commercial vessels that transport goods and passengers for profit. The importance of the mercantile marine cannot be underestimated in terms of global commerce and transportation.