General:
* Oral: Relating to the mouth, spoken.
* Orifice: An opening or hole, especially in the body.
* Oral cavity: The mouth.
* Oration: A formal speech.
* Oratory: The art of public speaking.
* Oral surgery: Surgery performed in the mouth.
More specific:
* Aorta: The main artery of the body, carrying blood from the heart.
* Oral history: Historical accounts based on interviews with people who experienced events firsthand.
* Oral fixation: In Freudian psychology, a fixation on oral activities like eating or smoking.
* Oral sex: Sexual activity involving the mouth.
Less common:
* Orofacial: Relating to the mouth and face.
* Oropharynx: The part of the pharynx that connects the mouth to the larynx.
* Oronasal: Relating to the mouth and nose.
Please note that some of these words may have other meanings not related to the Greek root "or."