Wiktionary
a. That cannot be reproduced or duplicated
WordNet
adj. impossible to reproduce or duplicate [syn: unreproducible] [ant: reproducible]
Usage examples of "irreproducible".
The most exciting questions are often unapproachable by experiment, because the effects you are trying to observe are just too small, below the level of sensitivity of the equipment you are using, or irreproducible because you can't control all the variables.
Indeed, except maybe for that female group in Evsoy, there was no one who could gainsay them if Ponter and Adikor simply claimed that the opening of the portal had been an irreproducible fluke.
The transformation of Seth Brundle (Jeff Goldblum) into an insect -- more precisely, into the monstrous hybrid Brundlefly -- is a statistical aberration: an improbable accident, a fortuitous encounter, an irreproducible singular event.