[Serious] Please convince me gender is binary

[Anomalocaris]

Really?  I always thought male meant "has a penis" and female meant "has a vagina."  What are these multiple meanings?

So you think, steeped in the stereotype of our society as you are.   The notion that gender is something fundamentally simply physical and not a compound trait that reflect an aggregate of several different physical and behavioral variables is certain not universal.

In some societies, it is the actual fulfilling of reproductive roles that define male and female.   So a Impotent man or a barren woman would not be considered to be male or female regardless of their possession of gender organs.   In others, male or femaleness are considered heavily social behavior dependent.   Those who frequently act a manner normally stereotyped as befitting the other gender would not be considered to be fully of the gender determined by their reproductive organs.