nucleosynthesis

This term describes the high-energy physical mechanism by which lighter elements fuse into heavier ones. It carries a clinical, scientific connotation and is used almost exclusively within the fields of astrophysics, cosmology, and nuclear physics to describe the origins of matter.

As a technical mass noun, it refers to the general process rather than a single event. It is treated as uncountable, meaning it does not typically take a plural form or a numerical modifier; one refers to the process of nucleosynthesis rather than a nucleosynthesis.