| ace in the hole |
a resource that remains unrevealed or unused until a particular need arises. |
| air hole |
an opening for the intake or discharge of air or gas. [3 definitions] |
| black hole |
a region or body in space with gravity so strong that neither light nor matter can escape it. Scientists believe that black holes form when very large stars collapse. |
| hole punch |
a tool for making small, round holes in paper, often used in order to fit paper into a ring binder; hole puncher. |
| hole puncher |
a tool for making small, round holes in paper, often used in order to fit paper into a ring binder; hole punch. |
| in the hole |
in strained or reduced circumstances. |
| ozone hole |
an area in the ozone layer where the ozone becomes thin. There is a large ozone hole over Antarctica and a smaller one over the North Pole. Scientists warn us this is dangerous. |
| swimming hole |
a pond or a deep spot in a river or stream that is used for swimming. |
| water hole |
a place in a dry area, such as desert, where water comes up from the ground and where animals come to drink. |
| watering hole |
a place where animals drink water, such as a spring. [2 definitions] |