Circa

Circa , usually abbreviated c. or ca. (also circ. or cca.), means "approximately" in the English language, usually referring to a date. Circa is widely used in genealogy and historical writing when the dates of events are not precisely known.

When used in date ranges, the term "circa" is applied before each approximate date, while dates without "circa" immediately preceding them are generally assumed to be known with certainty.

Examples:
* 1732–1799, both the years shown and the date range are precisely known
* –1799, only the second year shown is certain, the first year is approximately known
* 1732 – , in this case the first year is certain, and the second year is approximate
* – , both the years shown and the date range are approximately known

wikipedia link: Circa