means The real, solid matter or meaningful content of something — what it's actually made of or what it actually amounts to.

from From Latin substantia, 'that which stands beneath' — sub ('under') plus stare ('to stand'). The image is literal: substance is what stands underneath the surface and holds everything up. The word arrived in English through Old French in the medieval period, carrying both the philosophers' sense (the underlying essence of a thing) and the everyday one (stuff, wealth, the gist of a matter).