Objection 1: It would seem that femininity is variable, and defined by whichever woman you happen to ask, since femininity is merely "how women act", and different women act differently. Therefore, femininity is different in each woman, and can't be defined universally.
I answer that:
There is one "standard" of femininity, because God created one feminine nature. This nature is universal, and aspects of it are found in all women. The more women develop this nature, the more they become the creature God intended them to be, and thus, the more closely do they become united to Him and follow His Will.
Reply to Objection 1: If you are using a human-centered view of femininity, it is indeed true to define femininity by what individual women think it is. If you are using a God-centered view of femininity, it is true to define it as participation in that universal nature by which God distinguished the woman from the man, and gave her the qualities which suit her for the particular work He has set aside for her. Since we are to live according to God's definitions, not our own, the true definition of femininity is the God-centered one.