| on the q.t. |
(informal) in stealth or secret; quietly. |
| on the qui vive |
on the lookout; alert; watchful. |
| on the rebound |
just after the bounce of a ball or the like. [2 definitions] |
| on the road |
traveling, esp. as a salesperson, performer, or theatrical company. |
| on the rocks |
in a state of financial ruin. [2 definitions] |
| 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 upgrade |
improving, rising, or gaining importance. |
| on the uptake |
in understanding, realizing, or grasping. |
| on the wagon |
(informal) refraining from drinking alcohol. |
| on the warpath |
seeking, preparing for, or fighting in a war or warlike conflict. [2 definitions] |
| on the whole |
all things considered; in general; for the most part. |
| on the wrong tack |
pursuing an inappropriate or mistaken course of action; misguided. |
| ontic |
having true and ultimate existence. |
| on time |
at the correct time for an event that is planned. |
| on tiptoe |
standing or walking on the toes, esp. to proceed quietly or cautiously. [2 definitions] |
| onto |
to a position on or on top of. [2 definitions] |
| onto- |
existence; being. [2 definitions] |
| ontogeny |
the process of biological growth and development of a particular living organism. (Cf. phylogeny.) |