Assassination is the elimination of an enemy in order to ensure advancement and/or the resolution of conflict for yourself or someone you care about. In many cultures it has been regarded as preferable to any type of negotiation, including discussion, because it is quicker and the outcome is so tidy and final, and because the right words are sometimes so hard to find, whereas the right dagger simply isn't.
Assassination is the preferred method of advancement in dynastic succession, but since no one wants to admit this publicly it's important to not get caught. This need for secrecy also applies to current workplace and domestic situations, both of which cry out for assassinations on a daily basis.
Assassination differs from murder only by the fact that the word "ass" occurs twice within it - making it fun to say - whereas "murder" doesn't contain any sounds that a baby can't make.