What is the X in X-mas?
Old English brydguma "suitor," from bryd "bride" (see bride) + guma "man" (cf. Old Norse gumi, Old High German gomo, cognate with Latin homo "man;" see homunculus). Ending altered 16c. by folk etymology after groom (n.) "groom, boy, lad" (q.v.).
Common Germanic compound (cf. Old Saxon brudigumo, Old Norse bruðgumi, Old High German brutigomo, German Bräutigam), except in Gothic, which used bruþsfaþs, literally "bride's lord."