(n)the branch of engineering that deals with the interaction of surfaces in relative motion (as in bearings or gears): their design and friction and wear and lubrication
The Collaborative International Dictionary of English (GCIDE) v.0.53Collaborative International Dictionary (GCIDE)
n. [ tribo- + -ology. ] the study of the effects of friction on parts of machinery moving in contact with each other, and of methods, such as lubrication, to counteract negative effects such as wear. [ PJC ]