Umm most people gonna think that masculinity and femininity should be already understand and ur life experiences should've given u the knowledge of their definitions. Most will react like

to the OP's thread but I kinda get where he going with this.
However, like looks....whats masculine and what feminine can be subjective to a point. With gender equality, women working top jobs in the workforce, traditional roles shifting over the past years vs how things were in our grandparents era, etc. If u think about how men and women act and express themselves nowadays...I can see how gender roles can be confusing because its more gender fluidity. U have men who wear more skinny jeans, tight clothes, haircuts and styles like Odell Beckham, Future, Young Thug, etc., which can make some men look soft or effeminate or even flamboyant. Also, u see more women wearing masculine clothing along with more short boyish haircuts like that talk show lesbian host Ellen. Some feminine women can pull off the tomboy look and still come off as feminine but I notice I see more women who don't come across as very feminine. When going out in public....u see more gender fluidity with some folks. This is part of gender expression and some can mistake it as sex appeal to attract ur same sex. Then, u have some men nowadays who aren't about making their bread and some even have their women supporting them. That doesn't come off as masculine to me either.
Personally, I feel that masculinity is defined by behavior, appearance, mannerisms, aura, characteristics, etc. IMO, a man should be a provider and protector for his woman. Now, its hard to be a sole provider because most homes are designed for 2 incomes. I just feel that a man shouldn't be home all day and not willing to work and a woman should have some type of job to help him out as well. Power couples tend to do the best IMO. Then a man should be decisive and more assertive. He shouldn't take shyt from anyone. Women respect that more as well as other men. A man should strive to do his best to provide for himself first...then his wife and kids. As far as mannerisms...that's self explanatory but some men may have been around a lot of females growing up or his mom was so influential that he picked up on her mannerisms. Parents should strive to teach their kids how men should carry themselves and tailor their parenting techniques to the specific child.
Finally, men should be mentally strong too and not bytch out so quickly. Sometimes he should have the patience and ability to calm his woman down...though that can be tough cuz some women can be super bytchy and over emotional and love to nag. U cant have her bytching out and u doing the same. A man should be able to provide peace to the situation and have strength to overcome tough situations.