The word "威风凛凛" is formed by combining the compound "威风", meaning "prestige" or "powerful demeanor", with the reduplicated adjective "凛凛", which intensifies the sense of sternness or awe-inspiring presence. "威风" itself consists of 威 (authority) and 风 (demeanor), while "凛凛" repeats 凛 (stern/cold) to emphasize a formidable and imposing quality, resulting in an idiom that vividly depicts a majestic and commanding appearance.