You talking about REDOX reactions??
In which case:
Let's say you have a solution of dissolved metal ions. If you put another more reactive metal in that solution, it will displace the dissolved metal....which for your definition purpose is simply "A more reactive metal will displace a less reactive metal from a solution of it's ions"
In terms of the actual transfer of electrons, the more reactive metal, being more reactive, is willing to give it's electrons up...and the less reactive metal is willing to recieve them...so the metal ions in solution gain those free electrons...
so once again for your definition "The more reactive metal loses electrons more easily, or is more easily oxidised"