- The definition of hairbrained, another spelling for harebrained, is silly, ill-considered or unlikely to be effective.
A crazy scheme that you come up with that doesn't make much sense is an example of a hairbrained scheme.
Origin of hairbrainedby folk etymology after hair
Origin of hairbrainedVariant of harebrained.
(comparative more hairbrained, superlative most hairbrained)
- Alternative spelling of harebrained.