Merriam-Webster Collegiate Dictionary - friction

 noun  Etymology: earlier, therapeutic rubbing of the limbs, from Middle French, from Latin ~-, frictio, from fricare to rub; akin to Latin friare to crumble, and perhaps to Sanskrit bhri?anti they injure  Date: 1704  1.  a. the rubbing of one body against another  b. the force that resists relative motion between two bodies in contact  2. the clashing between two persons or parties of opposed views ; disagreement  3. sound produced by the movement of air through a narrow constriction in the mouth or glottis  • ~less adjective  • ~lessly adverb