ylem

A form of matter hypothesized by proponents of the Big Bang theory to have existed before the formation of the chemical elements.

In the Big Bang theory, the hot and dense plasma of which the cosmos consisted at the time of recombination in an early stage of its expansion and cooling, when the first atoms formed and photons decoupled, the source of the cosmic background radiation.

(cosmology) the original matter that (according to the big bang theory) existed before the formation of the chemical elements