An Etymological Dictionary of the German Language/prahlen

by Friedrich Kluge

prahlen, vb., ‘to parade, vaunt, boast,’ from MidHG. prâlen, ‘to make a noisy parade, shout’; comp. the equiv. Du. brallen and pralen, as well as E. to brawl. Its connection with Fr. brailer, ‘to bawl,’ and W. bragal, ‘to brag, bawl,’ is uncertain.