Hetero means different and homo means the same. So heterosexual means being attracted to the opposite sex ( normal)
The term is used to refer to people who are attracted romantically and sexually to individuals of the opposite sex. Hetero- comes from the Greek word heteros, meaning "different" and the Latin for sex .The term "heterosexual" was coined shortly after and opposite to the word "homosexual" by Karl Maria Kertbeny in 1868. 'Straight' is another slang that is used.one criticism of the use of this term is that "heterosexual" as too clinical and dehumanizing as the word only refers to one's sexual behavior.
Heterosexual means a person who prefers to have sexual and emotional relationship with members of the opposite gender.