An imaginary circle on the earth's surface passing through the North and South Poles is known as what?

The term that describes an imaginary circle on the Earth's surface passing through the North and South Poles is "Meridian." Meridians are lines of longitude that run from pole to pole and indicate the geographic coordinate system used for locating positions on the Earth's surface. Each meridian is defined by its angular distance east or west of the Prime Meridian, which is at 0 degrees longitude.

The other terms mentioned do not fit this definition. Latitude refers to the imaginary lines that run horizontally around the Earth, measuring the distance north or south of the equator. These lines are parallel to one another and do not pass through the poles. A degree is a unit of measurement used to express angles; it does not specifically identify a feature of the Earth's surface. A parallel, as stated earlier, refers to lines of latitude, which run parallel to the equator and never meet, differing from meridians that converge at the poles. Thus, the answer, "Meridian," is accurate as it directly relates to the circle that passes through both the North and South Poles.