"Oral" specifically refers to the mouth and the area around it; for example, an oral exam is a type of test in which the person being tested must deliver answers verbally. i.e by way of mouth.
Oral sex is a sexually intimate act in which the mouth of one participant is used to sexually stimulate another. The two most well-known examples of this, fellatio and cunnilingus, are mouth-to-penis and mouth-to-vagina, respectively.
Oralism is one of the two main approaches to providing education of deaf students.
This is inflammation of the oral cavity.