excessive or unnecessary expenditure or outlay of money.

an instance of this

That sports car is an inexcusable extravagance.

unrestrained or fantastic excess, as of actions or opinions.

an extravagant action, notion, etc.

the extravagances one commits in moments of stress.

noun

economy , moderation , providence , saving , thrift , thriftiness , frugality

noun

absurdity , amenity , dissipation , exaggeration , excess , exorbitance , expenditure , folly , frill , icing on the cake , immoderation , improvidence , lavishness , luxury , outrageousness , overdoing , overindulgence , overspending , preposterousness , prodigality , profligacy , profusion , recklessness , squander , squandering , superfluity , unreasonableness , unrestraint , unthrift , wastefulness , wildness , embarrassment , excessiveness , extravagancy , extravagantness , overabundance , plethora , superabundance , superfluousness , surfeit , profuseness , waste , enormity , enthusiasm , extravaganza , luxuriance , nimiety , opulence , rampancy , redundance , superflux , wantonness