His Majesty's Australian Ship

His Majesty's Australian Ship (HMAS) (or Her Majesty's Australian Ship when the monarch is female) is a ship prefix used for commissioned units of the Royal Australian Navy (RAN). This prefix is derived from HMS (Her/His Majesty's Ship), the prefix used by the Royal Navy of the United Kingdom, and can be equally applied to warships and shore bases (as Australia follows the British tradition of referring to naval establishments as stone frigates).^{[citation needed]}

By the early 21st century, especially when RAN vessels were deployed as part of international coalitions, an unofficial, alternative prefix was sometimes used: "Australian navy ship" (which was not abbreviated). This was typically used in communications at sea with other navies or merchant vessels. This avoided any confusion that may have resulted from RAN ("HMAS") vessels serving alongside British RN ("HMS)" vessels and/or those of other Commonwealth navies.^{[citation needed]}

On 10 July 1911,