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to crowd; to flock; to swarm
魚が群れて泳いでいる。
Fish are swimming in a school.
人気店の前には開店前から人が群れていた。
People had gathered in front of the popular shop even before it opened.
無邪気な子供たちは誰かの周りに群れるのが好きだ。
Young children love to flock around someone.