What is the X in X-mas?
c.1300, "essential nature," from Old French substance (12c.), from Latin substantia "being, essence, material," from substans, present participle of substare "stand firm, be under or present," from sub "up to, under" + stare "to stand," from PIE root *sta- "to stand" (see stet). A loan-translation of Greek hypostasis. Meaning "any kind of corporeal matter" is first attested mid-14c. Sense of "the matter of a study, discourse, etc." first recorded late 14c.
substance sub·stance (sŭb'stəns)
That which has mass and occupies space; matter.
A material of a particular kind or constitution.