Heterosexuality (noun)

1. Sexual attraction to people of the opposite sex.
2. The state of being heterosexual; the condition of being sexually attracted to people of the opposite sex.

Origin:

From the greek heteros meaning "other" and the latin sexualis meaning "pertaining to sex".

Examples:

1. John"s heterosexuality is not in question, he"s been married to a woman for 20 years.
2. She is open about her heterosexuality and never felt the need to hide it.
3. Heterosexuality is the most common sexual orientation.
4. Many people assume that everyone is heterosexual.
5. Studies have shown that heterosexuality is not a choice, it is biologically determined.