oc·tag·o·nal \(ˈ)äk|tagənəl, -taig-\adjective Etymology: alteration (influenced by octagon) of earlier octogonal, from Middle French, from octogone octagon (from Latin octagonum, octogonum) + -al : having eight sides < built a mansion in the shape of an octagon, which started quite a fashion for octagonal houses — Time > • oc·tag·o·nal·ly\-əlē, -əli\adverb