roer

RUR can refer to:Rur river in eastern Belgium, western Germany and southern Netherlands (not the Ruhr)R.U.R. (Rossum's Universal Robots), a science fiction play by Karel ČapekRussian ruble before 1997 (currency code RUR, today's ruble is RUB)
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The Rur -German, in Dutch and French: Roer, — not to be confused with the  Ruhr — is a river in  Belgium, Germany and the Netherlands. It is a right tributary to the river Meuse. About 90% of the river is in Germany.
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v. nibble, gnaw; pick

v. bite; grit, erode; gnaw, nibble

n. rudder, helm, handlebars, gun, rifle

v. stir, shake, froth, churn, whip, affect, agitate

= gnaw (at).
Ex: The rugby league is increasingly beset by a financial reward system that gnaws at its prime resource -- the players.
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* hueso duro de roer = uphill struggle, tough nut to crack, hard nut to crack.