| once and for all |
firmly and decisively, with absolute finality. [2 definitions] |
| once in a blue moon |
from time to time, but very rarely. |
| once in a while |
sometimes but not very often; occasionally. |
| once-over |
(informal) a hasty look at and evaluation of something or someone. |
| onchocerciasis |
a tropical disease transmitted by flies in which parasitic worms cause itchy rashes, skin lesions, blindness, and sometimes elephantiasis; river blindness. |
| oncidium |
any of various tropical orchids. |
| oncology |
the medical science concerned with cancer, esp. with tumors. |
| oncoming |
coming toward or near; approaching. [2 definitions] |
| on consignment |
of goods, sent to a selling agent, with payment to be made after the goods are sold. |
| on deck |
in baseball, next in line to bat. [2 definitions] |
| on draft |
available to be drawn from a keg or cask; not bottled. |
| on duty |
in the process of doing one's job. |
| -one |
a ketone, or a related or similar chemical compound containing oxygen. |
| one |
being single in number. [11 definitions] |
| one by one |
one at a time; one after another; singly. |
| on edge |
nervous or anxious; full of worry. [2 definitions] |
| one-digit number |
a whole number containing one digit, such as 2. |
| one for the road |
one last drink, esp. an alcoholic beverage, that is taken before departing. |
| one-horse |
designed for or using only one horse. [2 definitions] |
| Oneida |
a member of a tribe of North American Indians living in Canada and New York State and belonging to the Six Nations. [2 definitions] |
| oneiric |
of or relating to dreams. |