开幕 (kāi mù) literally means 'to open the curtain' — combining 开 (kāi, 'to open') and 幕 (mù, 'curtain' or 'screen'). Historically, it refers to the moment a theater performance begins when the curtain rises. Today, it’s used figuratively for the formal start of any major public event, such as conferences, exhibitions, sports games, or ceremonies. It emphasizes ceremony, significance, and official commencement.

The word is almost always used intransitively or with a specific event as its subject (e.g., the conference, the exhibition), and rarely takes a direct object. It commonly appears in news headlines, official announcements, and formal speech. While it can be used as a noun (e.g., 开幕式, 'opening ceremony'), the bare form 开幕 functions primarily as a verb meaning 'to open (officially).'