The headword, apparently a feminine noun, is otherwise unattested. A noun r(e/ka occurs a few times in Byzantine texts; according to the lexicon of E.A. Sophocles, this is "a kind of scourge." So the present headword may be related, with alphaiota substituted for the homophonous epsilon.
For the glossing term see mu 266 and under (e.g.) beta 455, upsilon 692, upsilon 693.