The definition of grandiose is something that is grand or magnificent or something that is trying to be impressive but is much too large, making it seem pretentious or overdone.(adjective)
An example of something that would be described as grandiose is an excessively large mansion decorated in an overdone way just to impress the neighbors.
See grandiose in Webster's New World College Dictionary
Origin: Fr < It grandioso < L grandis, great, grand
See grandiose in American Heritage Dictionary 4
Origin: , from Italian grandioso
Origin: , from grande, great
Origin: , from Latin grandis.
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