Subject + 定 + 了
定 (dìng) means "to settle," "to fix," or "to determine," indicating that something has been decided or made stable. It appears in many compound words and can function independently, as in 定了 (settled/decided).
下周的行程还没定呢。
xià zhōu de xíngchéng hái méi dìng ne.
The schedule for next week hasn't been decided yet.
我们定好了明天中午见面。
wǒmen dìng hǎo le míngtiān zhōngwǔ jiànmiàn.
We've agreed to meet tomorrow at noon.
你定了没有?快点决定吧。
nǐ dìng le méiyǒu? kuài diǎn juédìng ba.
Have you decided or not? Hurry up and make a decision.