Misgendering

The term misgendering means referring to somebody as if they had another gender identity. For example, using the he/him pronouns for a woman or the she/her pronouns for a nonbinary person who uses inclusive or nounself pronouns. This is one method transphobes can attack transgender and nonbinary people.

Unintentional Usage
It is common for someone to assume another person's gender identity based on parts of their gender expression, such as their voice, hair length or style, and clothing.