What is the definition for a test tube rack?

A test tube rack is a wooden or plastic holder of test tubes in a laboratory. It has several small holes, each of which holds one test tube in an upright position. Test tube racks help keep a lab organized. They come in a variety of sizes.

The items may be color coded, which helps with identification in the processing of multiple tube samples. Some racks support four-way linkage on both ends and sides. This allows several sections to be connected to store larger samples together in an organized way. High-quality test tube racks should resist chemical corrosion and be easy to clean and disinfect.