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1610s, a back-formation from obstruction or else from Latin obstructus, past participle of obstruere "to block, to stop up" (see obstruction). Related: Obstructed; obstructing.
obstruct ob·struct (əb-strŭkt', ŏb-)v. ob·struct·ed, ob·struct·ing, ob·structs To block or close a body passage so as to hinder or interrupt a flow.