a Graeco-Roman jurist, usually named COSMAS MAGISTER, probably because he filled the office of magister officiorum under Romanus Senior; although Reiz, in the index of proper names subjoined to his edition of Harmenopulus in the supplementary volume of Meermann's Thesaurus, is inclined to think that Magister was a family surname.
In Leunclavius (J. G. R. ii. pp. 166, 167) are two sententiae (Ψῆφοι) of Cosmas in the style of imperial constitutions, as if he had been authorized by Romanus to frame legal regulations. It further appears from a Novell of Romanus, published in the collection of Leunclavius (ii. p. 158), that Cosmas was employed by the emperor in the composition of his laws.
[J.T.G]