characterized by opposite extremes; completely opposed; "in diametric contradiction to his claims"; "diametrical (or opposite) points of view"; "opposite meanings"; "extreme and indefensible polar positions"
emphasis If you say that two things are diametrically opposed, you are emphasizing that they are completely different from each other. diametrically opposed/opposite completely different and opposite
as from opposite ends of a diameter; "when two honest witnesses give accounts of the same event that differ diametrically, how can anyone prove that the evidence you gave was deliberately false?"; "three of these brushes were approximately 120 feet apart and the fourth diametrically opposite to one of the three"