| originally |
at first. |
| originate |
to start or come into being. [2 definitions] |
| Orinoco River |
a major river of South America that starts near the Venezuelan border with Brazil, flows across Venezuela, then along the border with Colombia, and finally empties into the Atlantic Ocean. |
| oriole |
a songbird that can be found in many parts of the world. Males have black and bright yellow or orange feathers. There are two main groups of birds that are considered orioles. There are several different kinds of orioles in each group. |
| Orion |
a hunter and giant in Greek myth. [2 definitions] |
| ornament |
something that is added to make something more beautiful to look at; decoration. [2 definitions] |
| ornate |
having a lot of decoration; fancy. |
| ornery |
mean; stubborn. |
| ornithology |
the study of birds. |
| orphan |
a child whose parents have died. [2 definitions] |
| orphanage |
a place where orphans live and are cared for. |
| orthodontics |
(used with a singular verb) the branch of dental medicine that deals with the straightening of teeth. |
| orthodontist |
a dentist who works in the branch of dental medicine that deals with the straightening of teeth. |
| orthodox |
of, having to do with, or following what is believed or practiced by most other people. |
| Oslo |
the capital city of Norway. |
| osmosis |
the passage of a liquid through a membrane until the concentration is the same on both sides of the membrane. |
| ostrich |
a large, powerful African bird that can run very fast but cannot fly. It has two toes on each foot and no feathers on its long legs and neck. |
| other |
different from the one mentioned. [11 definitions] |
| otherwise |
in a different manner or other way. [3 definitions] |
| Ottawa |
the capital city of Canada. Ottawa is in the province of Ontario. [2 definitions] |
| otter |
a mammal with brown fur, a long body, short legs, and webbed feet. Otters live in the water where they eat fish, frogs, and other water animals. Different kinds of otters are found in most parts of the world. They live in groups and are very playful. Otters are related to skunks, badgers, and other kinds of weasels. |