| 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. |
| opossum |
any of a number of American marsupials that are active at night and live in trees. [2 definitions] |
| opossum shrimp |
a small shrimplike crustacean, the female of which carries her eggs in a pouch between the legs. |
| opp. |
abbreviation of "opposite." |
| opponent |
one who opposes; antagonist; foe. |
| opportune |
favorable or suitable, esp. in relation to time. |
| opportunism |
an act or the habitual practice of taking advantage of situations for one's own ends without considering principles or the effects on others. |
| opportunist |
one who tends to take advantage of situations to serve his or her own ends, especially without regard for others or of principles. |
| opportunistic |
seeking or taking advantage of situations to serve one's own ends, especially without regard for others or for principles. |
| opportunity |
a chance that makes something possible or that may bring about some benefit. [2 definitions] |
| opposable |
capable of being opposed or resisted. [2 definitions] |
| oppose |
to think, act, or be against; resist or obstruct. [3 definitions] |
| opposed |
not in favor of; against. |
| opposeless |
combined form of oppose. |
| opposite |
located at or on the sides opposing each other; facing. [7 definitions] |