Subject + 定为 + Category/Status
定为 (dìng wéi) is a verb phrase meaning "to designate as," "to set as," or "to determine as." It is used when officially assigning a status, category, or label to something. For example, a government might 定为 a particular year as a special commemorative year.
政府把每年的九月定为全民健身月。
Zhèngfǔ bǎ měi nián de jiǔ yuè dìng wéi quánmín jiànshēn yuè.
The government designated September each year as National Fitness Month.
法院将这起案件定为重大刑事案件。
Fǎyuàn jiāng zhè qǐ ànjiàn dìng wéi zhòngdà xíngshì ànjiàn.
The court classified this case as a major criminal case.
学校把周五定为无作业日,学生们都很开心。
Xuéxiào bǎ zhōuwǔ dìng wéi wú zuòyè rì, xuéshēngmen dōu hěn kāixīn.
The school designated Friday as a homework-free day, and the students were all very happy.