The Latin word circa, literally meaning about, is often used to describe various dates (often birth and death dates) that are uncertain. For example, one could say that Pearl Harbor was attacked circa (often abbreviated c. or ca.) 1941, if the year were uncertain. The further back in time a given date is, the broader the time period which circa encompasses:

• Within the last hundred years, circa should be accurate to within five years (e.g., 1940, 1945, 1950, 1955);
• Within the last five hundred years, circa should be accurate to within ten years (e.g., 1720, 1730, 1740, 1750);
• Within the last thousand years, circa should be accurate to within twenty-five years (e.g., 1250, 1275, 1300, 1325);
• Within the last two thousand years, circa should be accurate to within fifty years (e.g., 150s, 200s, 250s, 300s);
• Within the span of recorded human history, circa should be accurate to within one hundred to two hundred years.

Commercial Uses

Circa is a brand name in the skateboarding industry which makes shoes, clothing, and skateboards. Professional skateboarders can be signed to the Circa skateboarding team.