Definition of "commodore"

(military, nautical) A naval officer holding a rank between captain and rear admiral.

(nautical) A (temporary) commander over a collection of ships who is not an admiral.  examples

(nautical) The leading ship in a fleet of merchantmen.  examples

(nautical) The president of a yacht club.  examples

(nautical) A yacht-club president's vessel in a regatta.  examples

(military, nautical) Ellipsis of commodore admiral.

(US, military, nautical) A rear admiral (lower half).

(entomology) Any of various nymphalid butterflies of the Asian genus Parasarpa.