Meanings

returning something to its original state (e.g. of an apartment when moving out)

nuclear fuel

raw fuel

primary

primordium

Steppe Route (precursor to the Silk Road)

three principles on transfer of defense equipment and technology

original kanji form

lattice vacancy

nuclear physics

cancer of unknown primary

primary macroglobulinemia

minimax principle (in game theory, etc.)

atomic emission spectroscopy

atomic model

ingredient (of a crude drug)

plaintiff

moped bike

causal virus

original key (of a song)