小时 means 'hour' — a unit of time equal to 60 minutes. The character 小 (xiǎo) literally means 'small', and 时 (shí) means 'time' or 'hour'. Together, 小时 historically distinguished this smaller unit from larger time units like 日 (rì, 'day') or 年 (nián, 'year'), hence 'small time' → 'hour'. It is the standard, neutral term used in daily speech, schedules, science, and formal contexts.

This word functions as a countable noun and always follows a numeral or measure word: e.g., 一小时 (yī xiǎo shí, 'one hour'), 三小时 (sān xiǎo shí, 'three hours'). Unlike English, Chinese doesn’t use plural markers, so 小时 remains unchanged regardless of quantity. It’s commonly paired with verbs like 花 (huā, 'to spend'), 过 (guò, 'to pass'), or 需要 (xūyào, 'to need') to express duration or scheduling.