If your asking about what interactions mean in Science then this is the definition --> a mutual or reciprocal action; interacting.
If your asking for the physics definition for interactions mean then this is the definition --> transfer of energy between elementary particles or between an elementary particle and a field or between fields; mediated by gauge bosons.
Or, if your asking for what interactions mean in general then this is the definition --> 1 : mutually or reciprocally active. 2 : involving the actions or input of a user especially : of, relating to, or being a two-way electronic communication system (such as a telephone, cable television, or a computer) that involves a user's orders (as for information or merchandise) or responses (as to a poll).
Hope this helps you, and I hope you have a wonderful weekend and a wonderful Thanksgiving bye! Your welcome.
