Waste uranium from nuclear reactors is called

Uranium left after the fissile isotope has been extracted for fuel is called depleted uranium.

Enriched uranium is the opposite, having a raised share of the fissile isotope.

Fertile uranium refers to isotopes that can be converted into fissile material, not the spent residue.

Fissile uranium is the reactive isotope itself, not the leftover waste.

The stream depleted of uranium-235 is the depleted form.

Depleted uranium is very dense and has been used in armour and munitions.