(Νικόμαχος), a son of Aristotle by the slave Herpyllis. We are destitute of any particulars of his life. The following points are merely indicated by their several authorities. From the will of Aristotle, as given by Laertiu;, we infer that Nicomachus was a mere boy when the will was made, and that he was entrusted first to the care of tutors therein named, and then to the discretion of Nicanor, Aristotle's adopted son. We are told by the same authority that Theophrastus was his teacher. Eusebius (Praep. 15.2) states that, while still young, he died in war. (D. L. 5.1, 12, 35; Euseb. 1. c.; Suid. s. v. Νικόμαχζς.) He must have lived about B. C. 320.

His name, as an author, has become mixed tip with that of his illustrious father. Cicero (de Fin. 5.5) and Laertius (8.88) seem to attribute to him certain ethical writings that are generally ascribed to Aristotle. Some modern writers have assented to this, but on slender grounds. (Fabric. Bibl. Graec. vol. iii. p. 262.) It is not difficult to see how the mistake may have arisen. A portion of the moral writings of Aristotle bears the name of Ἠθικὰ Νικομαχεία, why we cannot tell; whether the father so named them, as a memorial of his affection to his young son, or whether they derived their title from being afterwards edited and commented on by Nicomachus. [See Vol. I. of this work, p. 331a. Ἠθικὰ Ἐυδήμεια.] This last reason is rendered not improbable from the circumstance mentioned by Suidas (l.c.), that Nicomachus wrote six books (probably a comment) on ethics, and a comment on his father's work Περὶτῆζ θυσικῆς Ἀκροάσεως. Hence the confusion between the editor and commentator, and the original author.