Antithetical means directly opposed in nature. Antithetical to everything he stood for, wholly antithetical, antithetical views.
It is stronger than different, since the two things are opposites rather than merely unlike. It takes to after it and belongs to argument rather than to description.
1adjectiveantitheticalDirectly opposed in nature.
“Secrecy of that kind is antithetical to the whole idea of a public inquiry.”
antithetical is a quality.
Greek antithetikos comes from antithesis, a setting against, from anti plus tithenai, to place.
From antitheticus + -al.
Etymology from Wiktionary, CC BY-SA