What is the X in X-mas?
Old English cenning "procreation; declaration in court," present participle of ken (v.). From early 14c. in senses "sign, token; teaching, instruction;" c.1400 as "mental cognition." From 1883 as "periphrastic expression in early Germanic poetry;" in this sense it probably is from Old Norse cognate verb kenna "to know, to recognize, to feel or perceive; to call, to name (in a formal poetic metaphor)."
"to know," Scottish dialect, from Old English cennan "make known, declare, acknowledge" (in late Old English also "to know"), originally "make to know," causative of cunnan "to become acquainted with, to know" (see can (v.)). Cognate with German kennen, Danish kjende, Swedish känna. Related: Kenned; kenning.
"range of sight," 1580s, a nautical abbreviation of kenning.
"house where thieves meet," 1560s, vagabonds' slang, probably a shortening of kennel.
A conformist, conventional man; a man lacking any but bland typical characteristics: Mr Quayle has been called a sort of Ken/ Bergin, the male villain, is reprising his role as the Ken-doll monster of Sleeping With the Enemy
[fr the male counterpart of the Barbie doll]
concise compound or figurative phrase replacing a common noun, especially in Old Germanic, Old Norse, and Old English poetry. A kenning is commonly a simple stock compound such as "whale-path" or "swan road" for "sea," "God's beacon" for "sun," or "ring-giver" for "king."