Excessive, immoderate, inordinate, extravagant, exorbitant, extreme are comparable when meaning characterized by going beyond or above its proper, just, or right limit.
Excessive implies an amount, quantity, or extent too great to be just, reasonable, or endurable.
Immoderate is often used interchangeably with excessive, but, distinctively, it may imply lack of restraint especially in the feelings or their expression.
Inordinate implies an exceeding of the bounds or limits prescribed by authority or dictated by good judgment.
Extravagant often adds to excessive or immoderate the implications of a wild, lawless, prodigal, or foolish wandering from proper restraints and accustomed bounds. The term often specifically implies prodigality in expenditure.
Exorbitant implies excessiveness marked by a departure from what is the customary or established amount or degree; it typically connotes extortion or excessive demands on the part of the agent or the infliction of hardships on the person affected.
Extreme implies an excessiveness or extravagance that seems to reach the end of what is possible; it is often hyperbolic in actual use.