fric·tion 
(frĭkshən)
(frĭkshən)n.
1. The rubbing of one object or surface against another.
2. Conflict, as between persons having dissimilar ideas or interests; clash.
3. Physics A force that resists the relative motion or tendency to such motion of two bodies or substances in contact.
[Latin frictiō, frictiōn-, from frictus, past participle of fricāre, to rub.]
friction·al adj.
friction·al·ly adv.