I’d say that you do need a dictionary. Self-defense and retaliation are not necessarily mutually exclusive. Self-defense generally describes the thwarting of an attack, not the prevention of one. One may also retaliate with no thought of defense–for vengeance, for example. One may fight a defensive battle without retaliating, or one may retaliate as a method of defending oneself.
It is simply wrong to declare that the U.N. allows only retaliation. What the U.N. charter does not permit is speculative pre-emptive attacks while pretending to defend oneself.
Had the resolution been legitimate, it would have authorized the U.S. to act with the U.N. to enforce the U.N. resolutions. Instead, the U.S. acted unilaterally, not to enforce U.N. directives, but for a whole host of shifting claims (from WoMD to regime change) that have little to no connection to the first Gulf War and had absolutely nothing to do with defending the U.S. against a third rate power on the far side of the Earth.