circa

• 源自拉丁语的前置词，主要用于日期、年份或数量前表示大约、接近，意为“大约”“左右”或“前后”；属正式、学术语体。

A preposition borrowed from Latin, used primarily with dates, years, or quantities to indicate approximation — meaning 'approximately', 'about', or 'around' in time or number; formal and academic register.

1. Approximately (in relation to time or date)C2formalscientific

   Used before a specific year, date, or time period to indicate that the stated time is an estimate rather than an exact figure; commonly found in historical, academic, and formal writing.

   大约，约

   • The Greek philosopher Socrates was born circa 470 BC.
   • This manuscript dates from circa 1100.
   • The building was constructed circa 1850.

2. Approximately (in relation to quantity or measure)C2formalscientific

   Used before a number, amount, or measurement to indicate that the figure is an approximation rather than an exact value; formal or scholarly usage.

   大约，约

   • The artifact is valued at circa $2 million.
   • The population was circa 50,000 at the time of the census.
   • The journey covered a distance of circa 300 miles.