The Roman soldier who smote our Lord with his spear. In the romance of King Arthur, this spear was brought by Joseph of Arimathea to Listenise, when he visited King Pellam, “who was nigh of Joseph's kin.” Sir Balim the Savage, being in want of a weapon, seized this spear, with which he wounded King Pellam. “Three whole countries were destoyed” by that one stroke, and Sir Balim saw “the people thereof lying dead on all sides.” (History of Prince Arthur, vol i. chap. 41.) Generally called LONGINUS.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894