agonic

a. [ Gr. &unr_; without angles; 'a priv. + &unr_; an angle. ] Not forming an angle. [ 1913 Webster ]

Agonic line (Physics), an imaginary line on the earth's surface passing through those places where the magnetic needle points to the true north; the line of no magnetic variation. There is one such line in the Western hemisphere, and another in the Eastern hemisphere. [ 1913 Webster ]