1620s, from Late Latin oralis, from Latin os (genitive oris) "mouth, opening, face, entrance," from PIE *os-/*ous- "mouth" (cf. Sanskrit asan "mouth," asyam "mouth, opening," Avestan ah-, Hittite aish, Middle Irish a "mouth," Old Norse oss "mouth of a river," Old English or "beginning, origin, front"). Psychological meaning "of the mouth as the focus of infantile sexual energy" (e.g. oral fixation) is from 1910. The sexual sense is first recorded 1948, in Kinsey. As a noun, "oral examination," attested from 1876. Related: Orally (c.1600); orality.
postoral post·o·ral (pōst-ôr'əl)
Situated behind or at the back of the mouth.
oral o·ral (ôr'əl)
Of or relating to the mouth.
Used in or taken through the mouth.
Of or relating to the first stage of psychosexual development in psychoanalytic theory, in which the mouth is the focus of exploration and pleasure.