The idea of nuclear fusion occurring at room temperature is called cold fusion.

"Hot" nuclear fusion (this is not the term normally used) is exactly what the name implies, the materials are heated, which provides them with enough energy to overcome the normal repulsion of protons.

Cold nuclear fusion requires no heating and has not yet been proved, although dozens of Physicists and Electro-Chemists have claimed to have created cold fusion. Cold Fusion relies on other forces, such as pressure, to overcome the electrostatic force of repulsion.

I think you mean "Cold Fusion"

It is the (currently) hypothetical nuclear fusion reaction which happens at ambient temperatures?

nuclear fusion

cant repeat the same process twice!,