Final answer:
A person whose biological sex aligns with their gender identity is called cisgender. This term contrasts with transgender, which describes individuals with a gender identity different from their sex assigned at birth.
Step-by-step explanation:
A person whose biological sex matches their gender identity is referred to as cisgender. This term comes from the Latin prefix "cis", meaning "on the same side" as opposed to "trans", which means "across".
While transgender individuals have a gender identity that differs from their sex assigned at birth, cisgender individuals align with the sex they were originally assigned.
This alignment does not affect or indicate a person's sexual orientation, gender, or gender expression; those are separate aspects of a person's identity.