What is the X in X-mas?
late 13c., "long, loose outer garment," from Old North French cloque (Old French cloche, cloke) "travelling cloak," from Medieval Latin clocca "travelers' cape," literally "a bell," so called from the garment's bell-like shape (the word is thus a doublet of clock (n.1)). An article of everyday wear in England through 16c., somewhat revived 19c. as a fashion garment. Cloak-and-dagger (adj.) attested from 1848, said to be ultimately translating French de cape et d'épée, suggestive of stealthy violence and intrigue.
Other "cloak and dagger pieces," as Bouterwek tells us the Spaniards call their intriguing comedies, might be tried advantageously in the night, .... ["Levana; or the Doctrine of Education," English translation, London, 1848]
c.1500, from cloak (n.). Figuratively from 1540s. Related: Cloaked; cloaking.
an upper garment, "an exterior tunic, wide and long, reaching to the ankles, but without sleeves" (Isa. 59:17). The word so rendered is elsewhere rendered "robe" or "mantle." It was worn by the high priest under the ephod (Ex. 28:31), by kings and others of rank (1 Sam. 15:27; Job 1:20; 2:12), and by women (2 Sam. 13:18). The word translated "cloke", i.e., outer garment, in Matt. 5:40 is in its plural form used of garments in general (Matt. 17:2; 26:65). The cloak mentioned here and in Luke 6:29 was the Greek himation, Latin pallium, and consisted of a large square piece of wollen cloth fastened round the shoulders, like the abba of the Arabs. This could be taken by a creditor (Ex. 22:26,27), but the coat or tunic (Gr. chiton) mentioned in Matt. 5:40 could not. The cloak which Paul "left at Troas" (2 Tim. 4:13) was the Roman paenula, a thick upper garment used chiefly in travelling as a protection from the weather. Some, however, have supposed that what Paul meant was a travelling-bag. In the Syriac version the word used means a bookcase. (See Dress.)