From Middle Egyptian, this feminine singular form was generally used for the plural. In Late Egyptian, the masculine singular form was used with all nouns.
James P[eter] Allen (2010) Middle Egyptian: An Introduction to the Language and Culture of Hieroglyphs, 2nd edition, Cambridge: Cambridge University Press, →ISBN, pages 89, 91–92.
^ Loprieno, Antonio (1995) Ancient Egyptian: A Linguistic Introduction, Cambridge: Cambridge University Press, →ISBN, page 58