Refers to three successive generations of a family, often used in contexts like 三世帯住宅 (three-generation household).
Three generations live together in this house.
third-generation immigrant; sansei
Specifically used for the grandchildren of Japanese immigrants, especially in the Americas. The term is well-known in Japanese-American communities.
the third (in a succession)
Used after a name to indicate the third person of that name in a dynasty or lineage, e.g., ヘンリー三世 (Henry III).
Henry III was the King of England.
He was born and raised in America as a third-generation Japanese-American.
三世 is the third generation (grandchild of the original immigrant), one step further than 二世, so learners must keep the generation numbers straight.
From 三 (three) + 世 (generation, world, reign). The immigrant sense is a direct extension of the generational meaning, widely used in Japanese diaspora communities.