If any woman, under pretence of asceticism, shall change her apparel and, instead of a womans accustomed clothing, shall put on that of a man, let her be anathema.
Ancient Epitome of Canon XIII.
Whatever women wear mens clothes, anathema to them.
The synodal letter in its sixth article also speaks of this. Exchange of dress, or the adoption by one sex of the dress of the other, was forbidden in the Pentateuch (Deut. xxii. 5), and was therefore most strictly interdicted by the whole ancient Church. Such p. 98 change of attire was formerly adopted mainly for theatrical purposes, or from effeminacy, wantonness, the furtherance of unchastity, or the like. The Eustathians, from quite opposite and hyper-ascetical reasons, had recommended women to assume male, that is probably monks attire, in order to show that for them, as the holy ones, there was no longer any distinction of sex; but the Church, also from ascetical reasons, forbade this change of attire, especially when joined to superstition and puritanical pride.
This canon is found in the Corpus Juris Canonici, Gratians Decretum, Pars I., Dist. xxx., c. vi.