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English definition of “RR”

RR

US

RR (TRAIN)

written abbreviation for railroad nounRailways and railway lines

RR (POST)

written abbreviation for rural route: used in addresses in some areas in the USThe postal systemRoutes and roads in general

RR (breathing)

specialized medical written abbreviation for respiratory rate (= the rate at which someone breathes in and out)
(Definition of RR from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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