heterosexual
The German word 'heterosexuell' is used to describe a person who is attracted to people of the opposite sex. It is a direct translation of the English word 'heterosexual'. In German, as in English, it is used as an adjective to describe a person's sexual orientation.
I am heterosexual.
This is a simple sentence declaring one's sexual orientation. In this case, the speaker is saying that they are heterosexual, meaning they are attracted to people of the opposite sex.
He always knew that he was heterosexual.
In this sentence, the speaker is talking about someone else's sexual orientation, pointed out the fact that this person has always known about his heterosexual orientation.
The heterosexual population makes up the majority.
This sentence is about the demographic distribution of sexual orientation in the general population. It asserts that heterosexual people, those attracted to the opposite sex, make up the majority.