[¦rap·id ‚prō‚tän ′kap·chər ‚prä‚ses] (astrophysics) A mode of explosive nucleosynthesis in which each of the nuclei lighter than iron captures many protons, populating nuclides near the proton drip line, and these subsequently undergo a series of beta decays back to one of the stable nuclides. Also known as rp-process.