| operetta |
a short light, usu. humorous opera, often with dialogue that is spoken as well as sung. |
| ophidian |
designating the biological suborder that comprises snakes. [2 definitions] |
| ophiolatry |
the attribution of divine power to snakes; worship of snakes. |
| ophiology |
the branch of zoology that deals with snakes. |
| ophthalmia |
inflammation of one or more parts of the eye, esp. the conjunctiva. |
| ophthalmic |
of or concerning the eye. |
| ophthalmo- |
eye. |
| ophthalmologist |
a doctor who specializes in the study and treatment of eye diseases. |
| ophthalmology |
the medical study of the eye, its diseases, and their treatments. |
| ophthalmoscope |
an instrument for examining the retina and the interior of the eyeball. |
| -opia |
a condition or defect of vision or of the eye. |
| opiate |
any of a number of drugs containing or derived from opium that induces calmness, stupor, or sleep, or relieves pain. [7 definitions] |
| opine |
to present or believe as one's own opinion. [2 definitions] |
| opinion |
what one thinks about a matter, esp. a judgment not necessarily based on fact alone. [5 definitions] |
| opinionated |
having definite and unchangeable opinions, often seemingly on all subjects. |
| opinionative |
of, like, or based on an opinion. [2 definitions] |
| opioid |
any natural or synthetic compound, including heroin, morphine, and certain prescription pain relievers, that binds opioid receptors and has an analgesic or narcotic effect. [2 definitions] |
| opioid epidemic |
a rapid increase in the use of prescription and non-prescription opioid drugs, beginning in the late 1990s and continuing into the early decades of the 2000s. |
| opioid receptor |
any of a group of protein molecules that bind opioids, resulting in an inhibitory response. |
| opium |
an addictive drug derived from one variety of poppy, containing various narcotic substances, and producing calm, stupor, sleep, or relief from pain. [2 definitions] |
| opium poppy |
a Eurasian annual poppy having grayish-green leaves and bearing large white, red, pink, or purple flowers, and oily seeds, the unripe pods of which may be harvested for their opium-containing sap. |