(of a black hole) A region of around a black hole where photons travel in orbits around the singularity, just beyond the event horizon.

(sex) A telephone line that a person calls to be sexually dominated.

Of or relating to Afghanistan, its people, or its language.

(graph theory) A graph derived from a given plane graph such that this derived graph has a vertex corresponding to each edge of the given graph, and such that for every “angle” (consecutive trio of...