A
prostitute. Usually,
prostitutes are females, but plenty of males are also prositutes.
Hookers sell their bodies to a variety of people, from unassuming men to really freaky characters. Just imagine having sex with half a dozen strange men each day for money it's not a pleasant thought.
And
prostitutes don't have sex for money because they like it; it's about the money.
Hookers range from the chic call girl, who has control over the situation, to the lowly streetwalker, who is vulnerable to attack.
And remember: use a condom if you're with a prostitute, unless you want clamydia, gonorrhea, herpes, AIDS, hepatitis, syphilis, or other *charming* diseases.