届时

• Pinyin: jiè shí
• Hanzi breakdown: 届 = 尸 + 由 — to arrive at, session; 时 = 日 + 寺 — time

Meaning

At that time; when the time comes. Referring to a future time already mentioned or understood.

A formal expression used in written Chinese and official announcements to refer to a specified future time. Often used in invitations, schedules, and formal notifications. More formal than 到时候.

Examples

1. 会议定于下周五举行，届时请准时参加。 The meeting is scheduled for next Friday; please attend on time.
2. 新系统将于明年一月上线，届时所有用户需重新注册。 The new system will launch in January next year; at that time all users will need to re-register.
3. 活动当天可能会下雨，届时请带好雨具。 It might rain on the day of the event; please bring rain gear at that time.

Usage Guide

Context: announcements, invitations, scheduling

Tone: official

Do Say

• 届时欢迎大家参加。(You are all welcome to attend at that time.)
• 届时我们会通知您。(We will notify you when the time comes.)

Don't Say

• 在口语中用'届时'代替'到时候' (Don't use 届时 instead of 到时候 in casual speech — it sounds too formal)

Origin & History

Composed of 届 (session; period; to arrive at) + 时 (time). Together they refer to the arrival of a specified time.

Cultural Context

Generation: All ages

Social background: Formal contexts