That the Eudemian Ethics is a genuine work of Aristotle, belonging to a middle stage in his development, is now widely accepted on the various grounds advanced by Jaeger and others from 1909 onwards. (From 1841 there had been universal acceptance of Spengel's ascription of the work to Eudemus himself.) I want to show (in section A) that, quite apart from those considerations, there is no reason to doubt the authenticity of E.E. on the ground of peculiarities in its vocabulary, as these can be explained in various ways. A presentation of the evidence as regards special vocabulary may in any case be of interest, and may throw some light eventually on its position among Aristotle's writings, if it belongs among them; and for this reason I add a further section (B) on words in E.E. uncommon in Aristotle.