We three brothers haven't been together for many years.
Tips
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Colloquial. 聚头 carries the warmth of an in-person reunion — friends, family, schoolmates. For a formal meeting you'd say 聚集 (jùjí) or 聚会 (jùhuì); for a business gathering, 开会 (kāihuì).
memory
Literally 'gather + heads': picture people leaning their heads in around a table. The Cantonese cousin 聚頭 (jeoi6 tau4) is also common — same image.