| on a dime |
(informal) with great quickness, precision, or accuracy. |
| on and on |
at excessive length. |
| on an even keel |
well-balanced or stable. |
| onanism |
self-gratification, esp. masturbation. [2 definitions] |
| on approval |
for determination of satisfaction, without obligation to buy. |
| on a silver platter |
without having to expend effort; undeservedly. |
| on bail |
temporarily released from custody after bail is given. |
| onboard |
transported, used, or installed upon a ship, aircraft, or other vehicle. [4 definitions] |
| once |
at one time in the past; formerly. [7 definitions] |
| 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. |