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English definition of “octagon”

octagon

noun [C] uk   /ˈɒk.tə.ɡən/ us    /ˈɑːk.tə.ɡɑːn/
a flat shape with eight sidesGeometrical shapesSpherical, circular and annular objects
octagonal
adjective uk   /ɒkˈtæɡ.ən.əl/ us    /ɑːk-/
an octagonal (= with eight sides) towerGeometrical shapesSpherical, circular and annular objects
(Definition of octagon from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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