What is the X in X-mas?
mid-15c., perhaps a diminutive of Old English helm "protection, covering; crown, helmet" (see helm (n.2)). But Barnhart says from Middle French helmet (Modern French heaume), diminutive of helme "helmet," from the same Germanic source as helm (n.2). "Middle English Dictionary" points to both without making a choice. "Old English helm never became an active term in the standard vocabulary of English." [Barnhart]
The foreskin of the penis or the end of the penis (glans penis) •Fr its shape: clipped helmet
(Heb. kob'a), a cap for the defence of the head (1 Sam. 17:5, 38). In the New Testament the Greek equivalent is used (Eph. 6:17; 1 Thess. 5:8). (See ARMS.)
defensive covering for the head, one of the most universal forms of armour. Helmets are usually thought of as military equipment, but they are also worn by firemen, miners, construction workers, riot and motorcycle police, gridiron-football and ice-hockey players, and bicyclists.