heptagon
n.
1560s, from Middle French heptagon, from Greek heptagonon, from hepta "seven" (cognate with Latin septem, Gothic sibun, Old English seofon; see seven) + gonia "angle" (see -gon). Related: Heptagonal.
〔李〕n.七角形 [-gon=a plane figure with...angles] ←hept（a）-[GK] =seven七