Never misgender transgender people

In 2004, Laverne Cox said that misgendering transgender people is an act of violence. Since then, she has repeated this statement for many times, however some other people still don't believe it. Why intentinally misgendering trans people is an act of violence? Why you shouldn't do it?

Misgendering is an act that referring to someone by the wrong gender, or implying that they are in a wrong gender. So, if you made mistakes in calling a boy "she" or refer to a boy as a girl, that's misgendering. You may misgender cis people or trans people, but it's rude when when misgemder trans people, and it's something that basically all trans people have to deal with at some point. Of course, there are time like trans dating when people intentionally misgender feminine cis boys or masculine cis girls as a way of trying reinforce arbitrary gender roles, and that's awful as well.
Violence is a harder thing to define. Several dictionaries say that it involves the physical force, including the Merriam-Webster and Oxford dictionary. However, dictionaries are not intended as all-knowing, unchangeable rule books. They change and adapt for many times as our usage changes, they always descriptive, instead of prescriptive, nowadays. I will argue that their definition of violence is not in style and it doesn't encompass all of the forms of violence we recognize today. And the world Health Organization agrees with me. In the 2002 world report on violence and health, the WHO define violence as "the intentional use of physical force or power, threatened or actual, against oneself, another person, or against a certain group and community, that either result in or has a high posibility of resulting in injury, death, psychological harm, maldevelopment, or deprivation." This definition is purposefully broad. The WHO showed in their recent report that violence is culturally influenced and varies widely across the globe. What some people see as violence, other may not. However, in an effort to fight violence worldwide, this is the definition that the world WHO came up with, and it explicitly includes non-physical forms of violence. They say "physical force or power", and they note that power isn't necessarily physical, it includes all types of social power imbalances. Their definition states that violence doesn't have to result in physical injury, instead it can result in psychological harm. Given that this is the definition that experts on the topic of violence have come up with, I would argue that it's much better and more effective definition than one currently listed in most dictionaries. Therefore, violence does include psychological violence, and misgendering a trans person is absolutely an act of psychological violence. If you still have a problem calling it violence, then call it aggression or abuse or whatever you want. The point is, it's a bad thing that we shouldn't do. Asks any trans person, and they can tell you how awful being misgendered makes them feel. It's a way of invalidating their identity. It makes them feel disrespected, isolated uncomfortable, and hated simply because of their gender. Misgenderring transgender people causes psychological harms.