Definitions

1. noun

indicating a date or period of time which is approximately known or intended, but not exactly stated or known

“The painting was created circa 1850.”

2. adverb

approximately or about (a particular time or date)

“The company was founded circa 2010 and has been growing rapidly since then.”

3. preposition

around or approximately the time of

“The event took place circa 10 am yesterday.”