订婚 (dìng hūn) literally combines 订 (dìng), meaning 'to fix', 'to arrange', or 'to formalize', and 婚 (hūn), meaning 'marriage'. Together, they denote the formal act of becoming engaged — a public declaration that two people intend to marry, often marked by a ceremony, exchange of gifts (like rings or betrothal presents), and agreement between families. It is a culturally significant step in Chinese society, emphasizing mutual commitment and familial approval before the wedding.

This term focuses on the contractual and social aspect of engagement rather than romantic feelings alone. While it can be used as a noun (e.g., 他们的订婚很隆重), its primary grammatical function is verbal: it describes the action of getting engaged. It’s commonly used in both spoken and written contexts — in news reports about celebrities, family conversations, or wedding planning discussions — and carries a tone of seriousness and tradition.