ETYM Latin invincibilis: cf. French invincible. Related to In- not, and Vincible.
Incapable of being overcome or subdued; SYN. unbeatable, unvanquishable.

HMS British battle cruiser. In World War I, Invincible took part in the battles of Heligoland Bight and the Falkland Islands 1914, and was sunk at the battle of Jutland 31 May 1916.