electromotive forcenoun
uk/i.lek.trəˌməʊ.tɪv ˈfɔːs//i.lek.trəˌmoʊ.t̬ɪv ˈfɔːrs/abbreviation emf specialized[ C or U ] the force of an electric current produced by any device that supplies electrical energy:
The volt is the SI derived unit of electromotive force, commonly called "voltage".
He invented an improved thermopile for measuring small electromotive forces.