O sign

The open-mouthed, slack-jawed appearance of an unconscious person, often an alcoholic in A&E/ER who may be sleeping off the previous night’s overindulgence. The O sign is also well-described in bedridden elderly patients with dementia

O sign

Medtalk The open-mouthed slack-jawed appearance of the narcotized, unconscious, stuporose, and dead-drunk. Cf Q sign.