adjective

(of a new invention or product) based on untested ideas or techniques and not yet established or finalized.

an experimental drug

exploratory,investigational,probing,fact-finding,trial and error,trial,test,pilot,speculative,conjectural,hypothetical,tentative,preliminary,probationary,prototype,under review,under the microscope,on the drawing board,empirical,observational,untested,untried