Circa
Circa (fromLatin, meaning "around, about"), usually abbreviated c., ca or ca. (also circ. or cca.), means "approximately" in several European languages including English, usually in reference to a date. Circa is widely used in genealogy and historical writing when the dates of events are not accurately known. When used in date ranges, circa is applied before each approximate date, while dates without circa immediately preceding them are generally assumed to be known with certainty.
For example: