Longman Dictionary English From Longman Dictionary of Contemporary EnglishRelated topics: Shapes, patterns, Mathsheptagonhep‧ta‧gon /ˈheptəɡən $ -ɡɑːn/ noun [countable] CFa shape with seven straight sides → polygon —heptagonal /hepˈtæɡənəl/ adjectiveOrigin heptagon (1500-1600) Greek heptagonos, from hepta “seven” + gonia “angle” ldoceonline.com
