What is the X in X-mas?
1898, coined by its discoverers, Sir William Ramsay and Morris W. Travers, from Greek neon, neuter of neos "new" (see new); so called because it was newly discovered. Neon sign is attested from 1927.
neon ne·on (nē'ŏn')
A rare inert colorless gaseous element that occurs in air and glows reddish orange in an electric discharge. Atomic number 10; atomic weight 20.180; melting point -248.59°C; boiling point -246.08°C.
A rare colorless element in the noble gas group that occurs naturally in extremely small amounts in the atmosphere. It glows reddish orange when electricity passes through it, as in a tube in an electric neon light. Neon is also used for refrigeration. Atomic number 10; atomic weight 20.180; melting point -248.67°C; boiling point -245.95°C. See Periodic Table.