/ ˈɪnrəʊd; NAmE -roʊd/ noun
inroad (into sth) something that is achieved, especially by reducing the power or success of sth else :
This deal is their first major inroad into the American market.
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IDIOMS
- make inroads into / on sth
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WORD ORIGIN
mid 16th cent. (originally referring to a hostile attack or raid): from in + road (from an early use in the sense riding ).