noun
Refers to social or political force, authority, or influence that someone or some group can exert. Common in the phrase 威勢を振るう, meaning to wield power or hold sway.
かつてその一族はこの町で威勢を振るっていた。
That family once wielded great influence in this town.
noun
vigor; energy; boldness; high spirits
Describes lively, forceful, or bold spirit, often in expressions such as 威勢がいい and 威勢よく. It can be positive, but may also imply loud bravado depending on context.
市場では店員たちが威勢よく客に声をかけていた。
At the market, the shop staff were energetically calling out to customers.
彼は威勢のいいことを言ったが、結局何もしなかった。
He talked boldly, but in the end he did nothing.