Definitions
from Wiktionary, Creative Commons Attribution/ShareAlike License
 n. A circle that passes through every vertex of a given triangle (or other polygon where possible)
from The Century Dictionary and Cyclopedia
 n. In mathematics, a circumscribed circle.
Etymologies
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Examples

←→ ←→ In Figure 5.24, point P is on the circumcircle of ABC.

Begin by considering the circumcircle of ABC (see Figure 6.5).

For example, the perpendiculars drawn to the three sides of a triangle from any point on its circumcircle intersect the sides in three collinear points (Simson's invariant).

Simson's Theorem The feet of the perpendiculars drawn from any point on the circumcircle of a triangle to the sides of the triangle are collinear.

As an example consider what the circumcircle of a triangle that has all 3 of its points being collinear would look like, how would you write the routine to be robust, when would you need to have a robust routine like that?

AD, BE&CF are cevians (not necessarily congruent) in triangleABCintersecting the circumcircle at P, Q, R (details)?
oroboros commented on the word circumcircle
Close to round: circa circumcircle
November 29, 2008
bilby commented on the word circumcircle
I think it's round.
November 28, 2008