The definition of hairbrained, another spelling for harebrained, is silly, ill-considered or unlikely to be effective.(adjective)
A crazy scheme that you come up with that doesn't make much sense is an example of a hairbrained scheme.
See hairbrained in Webster's New World College Dictionary
Origin: by folk etym. after hair
See hairbrained in American Heritage Dictionary 4
Origin: Variant of harebrained.
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