Excess is a related term of lavishness.
As nouns the difference between excess and lavishness
is that
excess is the state of surpassing or going beyond limits; the being of a measure beyond sufficiency, necessity, or duty; that which exceeds what is usual or proper; immoderateness; superfluity; superabundance; extravagance; as, an excess of provisions or of light while
lavishness is the state or characteristic of being lavish.
As an adjective excess
is more than is normal, necessary or specified.