Monosexual

Monosexual refers to someone who is attracted exclusively to a single gender. Monosexual refers both to exclusively gay individuals, straight individuals, and anyone else who is attracted to a single gender. It is typically used by bisexuals/multisexuals to refer to anyone who is not bi-spec or m-spec (with the exception of individuals who are both aromantic and asexual, as they are sexually/romantically attracted to zero genders). It is similar to the terms cisgender or allosexual in that way. It is commonly used when talking about monosexism; the prejudice against bisexuality/multisexuality.

The romantic counterpart to monosexual is monoromantic. The opposite of monosexual is multisexual.

Flag
The monosexual flag was created by Tumblr user beyond-mogai-pride-flags on November 14th of 2018. It has no confirmed meaning.

Monosexism
Monosexism is the belief that monosexuality (either exclusive heterosexuality and/or homosexuality) is superior to or more legitimate than multisexuality. It is, at its root, a form of biphobia.

Monosexists see bisexuality as morally wrong, as sinful, dangerous, or deviant. Some gay individuals dismiss bisexuals as lacking in self-acceptance, and claim that bisexuals are actually gay but are in denial. Others see bisexuals as trying to maintain straight privilege while simultaneously trying to get into LGBT+ spaces.

Another common attitude toward bisexuality, especially among heterosexual individuals, is the fear that their bisexual partner will leave them for a member of the same gender. Similar fears exist among gay individuals as well, leading to the stereotype that bisexuals are more likely to cheat. There is a belief that multisexuals will eventually get married and "choose a side", dismissing the fact that multisexuals are still attracted to multiple genders after they are married.