(exp) great vigor; tremendous energy; forceful enough to knock down birds in flight
→Related words:
飛ぶ鳥を落とす勢い
彼、今のところは飛ぶ鳥も落とす勢いだけれど、あの威勢いつまでもつのか、疑問だね。
He's unstoppable right now but the question is how long he can remain at the pinnacle of his career.