Heterosexual refers to the sexual orientation of someone who is attracted to people of a different gender or sex than their own, commonly meaning a woman attracted to men or a man attracted to women. Heterosexual people often refer to themselves as ‘straight’.
A person who is both cisgender and heterosexual is sometimes referred to as “cishet”.
Heteroromantic would refer to someone who has romantic attraction to people of a different gender from their own.
Other definitions/things to note:
Heterosexual attraction is often characterised as attraction to the “opposite” gender or sex; however, this is based on the gender binary (the assumption that people can only be one of two genders).