'任期届满' literally combines '任' (to assume office), '期' (period, term), '届' (a completed cycle or session), and '满' (full, complete). Together, it means the formal expiration of an official’s designated period in office — not just time passing, but the legal or procedural conclusion of a mandated service term. It is used almost exclusively for elected or appointed officials (e.g., mayors, directors, committee members) whose roles are defined by fixed durations.

This phrase carries institutional weight and appears in formal announcements, news reports, government documents, and election-related contexts. It implies that the position becomes vacant unless reappointment or re-election occurs. Unlike casual expressions like '到期' (expires), '任期届满' emphasizes structural legitimacy and procedural transition — it signals not only time’s end but also the opening of succession processes such as elections or nominations.