RUB
Rub, n. Etym: [Cf. W. rhwb. See Rub, v,t,]

1. The act of rubbing; friction.

2. That which rubs; that which tends to hinder or obstruct motion or progress; hindrance; obstruction, an impediment; especially, a difficulty or obstruction hard to overcome; a pinch. Every rub is smoothed on our way. Shak. To sleep, perchance to dream; ay, there's the rub. Shak. Upon this rub, the English ambassadors thought fit to demur. Hayward. One knows not, certainly, what other rubs might have been ordained for us by a wise Providence. W. Besant.

3. Inequality of surface, as of the ground in the game of bowls; unevenness. Shak.

4. Something grating to the feelings; sarcasm; joke; as, a hard rub.

5. Imperfection; failing; fault. [Obs.] Beau. & Fl.

6. A chance. [Obs.] Flight shall leave no Greek a rub. Chapman.

7. A stone, commonly flat, used to sharpen cutting tools; a whetstone; — called also rubstone. Rub iron, an iron guard on a wagon body, against which a wheel rubs when cramped too much.

RUBA-DUB
Rub"a-dub, n.

Defn: The sound of a drum when continuously beaten; hence, a clamorous, repeated sound; a clatter. The rubadub of the abolition presses. D. Webster.