Subject + 定 + 在 + Time/Place
定 (dìng) means "to set," "to fix," or "to determine" and is used when establishing a time, plan, rule, or decision. It conveys finality or firmness about an arrangement. Common collocations include 定在 (set at a specific time), 决定 (to decide), and 规定 (to stipulate).
会议时间定在下周三上午十点。
huìyì shíjiān dìng zài xià zhōusān shàngwǔ shí diǎn.
The meeting is scheduled for 10 a.m. next Wednesday.
我们先把计划定下来再说吧。
wǒmen xiān bǎ jìhuà dìng xiàlái zài shuō ba.
Let's finalize the plan first before we talk about anything else.
老板定了一个新规矩,不许上班迟到。
lǎobǎn dìngle yí gè xīn guījǔ, bù xǔ shàngbān chídào.
The boss set a new rule: no being late to work.