WordNet records no synonym and no antonym for experimentalism. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
an empirical doctrine that advocates experimental principles
an orientation that favors experimentation and innovation
“the children of psychologists are often raised in an atmosphere of experimentalism”
Synonyms, antonyms and the broader and narrower relations for experimentalism come from Princeton University’s WordNet. Full sources and licences.