(a) a senior commanding officer of a naval fleet or navy; (in Britain, Australia and other countries) spec. (the title of) an officer of the…

A ship commanded by or carrying an admiral; = flagship, n. 1; (also) the leading or principal ship of any fleet. Cf. admiral, n. 3.

= admiral ship, n.1 Now historical.

A vessel (or the head of a squadron of vessels) sailing behind (the squadron of) a vice admiral, and commanded by a lower-ranking officer. Obsolete.

A vessel commanded by a vice-admiral. Obsolete.

Nautical. A ship carrying an admiral's flag, a flagship.

A ship bearing an admiral's flag.