<p>In the animal ethics literature, speciesism is defined in all sorts of manners. It is construed as a behaviour or a philosophical view, as necessarily anthropocentric or possibly centred on other species, as involving the idea that species membership is morally significant or compatible with the rejection of that idea, as necessarily immoral or possibly ethically acceptable. Up to a point, this variety is unobjectionable. We are at liberty to stipulate the sense in which we use words. But this is true only within limits. Some definitions are good and some bad, depending on whether or not they meet certain conditions. In this contribution, I define speciesism as unequal treatment based on species and argue that this definition fares better than extant accounts insofar as it satisfies two desiderata: matching a good account of racism and making the concept of speciesism most useful.</p>