tripod
A three-legged stand that holds a camera or tool steady.
A tripod is a three-legged stand used to hold something steady, most commonly a camera or telescope.
If you've ever tried to take a photograph in dim light or zoom in close on something far away, you know how hard it is to hold perfectly still. Even the tiniest shake blurs the image. A tripod solves this problem by providing rock-solid support. Photographers use tripods for long-exposure shots of the night sky, where the camera needs to stay completely motionless for several seconds or even minutes to capture enough light from distant stars.
Scientists use tripods to hold surveying equipment when measuring land or construction sites. Artists sometimes mount cameras on tripods to film themselves working. The three-leg design is remarkably clever: three points always form a stable plane, even on uneven ground, while four legs might wobble if the surface isn't perfectly flat.
You might also hear tripod used metaphorically to describe anything supported by three essential elements, like a “tripod of success” resting on hard work, creativity, and persistence.