Tube/tuːb/ Definition 1 of 4Pro Tip 1/3Industrial Context The term is often used in construction, plumbing, or laboratory settings. The workers installed a new water tube in the building. Pro Tip 2/3Scientific Use In science, 'tube' may refer to specialized equipment, like a test tube. Pour the solution into the tube carefully. Pro Tip 3/3Shape Recognition Anything cylindrical and hollow can be referred to as a 'tube'. We used cardboard tubes for our art project.