IPA: //ˈbræʃ.ɪst//
KK: /bræʃɪst/
Very bold or rude in a way that shows a lack of respect for others; the most extreme version of being brash.
His brashest comments often offended his colleagues.
Comparative: brashier
Superlative: brashest
Brashest is derived from the adjective "brash" (originating from the Middle English "brash", meaning rash or impetuous), with the superlative suffix "-est" (indicating the highest degree). The word "brashest" refers to the most impetuous or reckless in behavior or attitude.
Think of someone who is the most 'impetuous' or 'rash' — that's what 'brashest' means, indicating the highest degree of being brash.