| on one's toes |
(informal) alert and ready to respond or act. |
| on purpose |
deliberately; intentionally. |
| onset |
the early stage; beginning. [2 definitions] |
| on tap |
ready to be served from a cask, as beer or ale. [2 definitions] |
| Ontario |
a south central Canadian province on the Great Lakes. [2 definitions] |
| on the air |
broadcast on radio or television. |
| on the average |
usually; ordinarily. |
| on the ball |
acting with efficiency and competence. [2 definitions] |
| on the blink |
not functioning; needing repair. |
| on the contrary |
in contradiction to something already said. |
| on the dot |
(informal) exactly on time; punctually. |
| on the double |
(informal) right away; immediately. |
| on the house |
free, as a gift from a business establishment. |
| on the mend |
getting better, esp. in health; recuperating. |
| on the off chance |
with the very slight likelihood; against the faint hope. |
| on the shelf |
inactive or unused; put aside; reserved for future use or consideration. |
| on the sly |
secretly; stealthily. |
| on the spot |
at once; immediately. [2 definitions] |
| on the spur of the moment |
without much thought; on a sudden impulse. |
| on the whole |
all things considered; in general; for the most part. |
| on tiptoe |
standing or walking on the toes, esp. to proceed quietly or cautiously. [2 definitions] |