Rub

a quarrel or impediment; “there's the rub ,” i.e., that is the difficulty.—Shakspeare and L'Estrange.
To rub: To run away. Don't rub us to the whit; don't send us to Newgate.--To rub up; to refresh: to rub up one's memory. A rub: an impediment. A rubber; the best two out of three. To win a rubber: to win two games out of three.