heterosexual

Short definition from Wiktionary

Adjective

1. 1
   Sexually attracted to members of the opposite sex.
2. 2
   Between two people of different sex.
3. 3
   Having a sexual desire for the opposite sex seen as unhealthy, including a proclivity for nonreproductive sex.

Noun

1. 1
   A heterosexual person, or other heterosexual organism.