At the level of particle physics interactions, the concept of force is relevant as momentum transfer, dp/dt. All Feynman diagrams that describe the mathematics of the interactions transfer a dp/dt at the vertices the momentum carried by the intermediary particles. Take the simple [Compton scattering][1]: [![compt][2]][2] the force is carried by the virtual electron, from the incoming real particles to the outgoing real particles. The term "fundamental forces" is in order to clarify that there are three coupling constants with different strengths, qualifying the vertices, electromagnetic, weak, strong, and these are identified as fundamental , because they are fundamental in building up the $SU(3)\times SU(2)\times U(1)$ [model of particle physics.][3] Each "fundamental force" with its own gauge bosons, "force", because the couplings define how strong the interaction is. [1]: https://en.wikipedia.org/wiki/File:Compton_Scattering_Feynman_Diagram.png [2]: https://i.sstatic.net/Ftulam.png [3]: https://en.wikipedia.org/wiki/Standard_Model