experimental /ɪkspɛɹəˈmɛntəl/adjective 4noun 1forms 3 adjective4 •Pertaining to or founded on experiment.Chemistry is an experimental science. •Experiential, empirical. •Serving as an experiment; serving to experiment.In its sixty-year history here, some 4,170 engines of the 4-6-0 type have been constructed. This is the vast sequel of that bold experimental step of the Highland Railway in 1894. — 1954 •Serving to be experimented upon; used in an experiment. noun1 •The subject of an experiment. formsexperimentals · more experimental · most experimental