Thank you, everyone, for responding. Femininity is a complex topic. We need to consider both the social constructs of feminine appearance and behavior and roles. Our personal opinions are a response to the social constructs amplified, denied, confirmed, or rebelled against.
For me, femininity is a collection of behaviors and attitudes that are reflected in appearance and mannerisms; these are dependent on the specific situation and the role I fill within that context.
At work I chair meetings, go toe-to-toe with my boss, freely offer opinions, inform co-workers when their lack of performance impacts my ability to do my job, and willingly chastise people who patronize or otherwise belittle me. I am more assertive at work. My appearance is always business conservative.
At social events (professional or personal) I flirt a little with the guys (smile, glance sideways, touch an arm), am less open with opinions, will not publicly criticize or chastise, and prefer to defer to a male companion (if I came with one). My appearance is suited for the occasion: jeans or dress, makeup, hair, jewelery.
Although I prefer to behave with a quiet manner, I will kick ass and take names if necessary.