Definition of "diametrically"
adverb
comparative more diametrically, superlative most diametrically
(especially in the phrase diametrically opposed) Absolutely (in opposition).
Quotations
"I do not see that we are at all called upon to pay so costly a compliment to society, as to assume a character diametrically opposed to our real one,—to utter sentiments we secretly disbelieve,—and to be as angry with our better nature for bursting from restraint, as at other times with our own inferior nature for refusing to submit to it.
1831, L[etitia] E[lizabeth] L[andon], Romance and Reality. […], volume I, London: Henry Colburn and Richard Bentley, […], pages 141–142