Same or similar entry in other lexica; references at Photius alpha1312 Theodoridis. The headword, transmitted as a)mfi/dea, should actually (as Reizenstein realised) be the feminine nominative plural a)mfide/ai. It is generated by Herodotus 2.69.2 (accusative plural there), as glosses to that passage show; cf. alpha 1714, and see also alpha 1715.
The term literally means anything that is bound around; see LSJ at web address 1.