What is the X in X-mas?
Old English hælftre "rope for leading a horse," from West Germanic *halftra- "that by which something is held" (cf. Old Saxon haliftra "halter," Old High German halftra, Middle Dutch halfter; see helve). In women's clothing sense, originally "strap attached to the top of a backless bodice and looped around the neck," 1935, later extended to the tops themselves.
"a stop, a halting," 1590s, from French halte (16c.) or Italian alto, ultimately from German Halt, imperative from Old High German halten "to hold" (see hold (v.)). A German military command borrowed into the Romanic languages 16c. The verb in this sense is from 1650s, from the noun. Related: Halted; halting.
"lame," in Old English lemphalt "limping," from Proto-Germanic *haltaz (cf. Old Saxon, Old Frisian halt, Old Norse haltr, Old High German halz, Gothic halts "lame"), from PIE *keld-, from root *kel- "to strike, cut," with derivatives meaning "something broken or cut off" (cf. Russian koldyka "lame," Greek kolobos "broken, curtailed"). The noun meaning "one who limps; the lame collectively" is from c.1200.
lame on the feet (Gen. 32:31; Ps. 38:17). To "halt between two opinions" (1 Kings 18:21) is supposed by some to be an expression used in "allusion to birds, which hop from spray to spray, forwards and backwards." The LXX. render the expression "How long go ye lame on both knees?" The Hebrew verb rendered "halt" is used of the irregular dance ("leaped upon") around the altar (ver. 26). It indicates a lame, uncertain gait, going now in one direction, now in another, in the frenzy of wild leaping.