七天 literally means 'seven days' and functions as a noun or numeral phrase indicating a duration of exactly one week. The character 七 (qī) is the cardinal number 'seven', while 天 (tiān) means 'day'—a unit of time, not 'sky' or 'heaven' in this context. Together, they form a fixed, uninflected time expression commonly used to specify periods in schedules, deadlines, recovery timelines, or event durations.

This phrase appears frequently in spoken and written Chinese—for instance, in weather forecasts ('未来七天有雨'), medical instructions ('服药七天'), or travel plans ('休假七天'). Unlike English, Chinese doesn’t use articles or plural markers here: 七天 is always singular in form and meaning. It’s neutral in register and appropriate in formal reports, casual conversation, and official notices alike.