Friction is the force that happens when two surfaces rub against each other and resist motion. It creates resistance or stickiness between objects. Full definition
Although the mass of the tub and gravity did not change, the coefficient of friction of the two ramp systems did. (scientificamerican.com)
The transmission's software has been further improved and additional economy has been achieved by reducing friction between transmission components. (greencarcongress.com)
Economic integration reduces friction in the marketplace, leading to faster growth. (firstthings.com)