/ ˈɒktəgən; NAmE ˈɑːktəgɑːn/ noun
( geometry ) a flat shape with eight straight sides and eight angles
► oc·tag·on·al / ɒkˈtægənl; NAmE ɑːkˈt-/ adjective :
an octagonal coin
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WORD ORIGIN
late 16th cent.: via Latin from Greek octagōnos eight-angled.