An ellipse has two of these

FOCI

Consider the points that define the shape's unique geometric property.

An ellipse is a type of oval shape, and in geometry, it has two fixed points called foci. The clue is straightforward—it’s asking for the plural term for these points, which is "foci." There’s no wordplay here; it’s a direct reference to a mathematical property of an ellipse. If you know basic geometry, this one should be easy to spot.