A "sturdy object" refers to something that is strong, solid, and unlikely to easily break or be damaged. It can withstand pressure or force without falling apart.
Sentences with «sturdy object»
If it's too hard to perform on your own, you can hold on to a rack or other sturdy object for stability. (onnit.com)
These give you many options as you can attach them as well to sturdy objects for extensions. (findperfectdiet.com)
Set up an item like a kitchen chair, a step stool, or some other sturdy object on legs. (mnn.com)