What is the X in X-mas?
1570s, originally "four-footed stand for a barrel," probably from Old North French gantier (Old French chantier, 13c., "store-room, stock-room"), from Latin cantherius "rafter, frame," also "a gelding," from Greek kanthelios "pack ass," related to kanthelion "rafter," of unknown origin. The connecting notion in all this seems to be framework for carrying things. Meaning "frame for a crane, etc." is from 1810. Railway signal sense attested by 1889.