parallelogrammatic
/ˌparəlɛləɡrəˈmatɪk/rare
adjective
Relating to, based on, or having the form of a parallelogram.
Origin
Early 18th century; earliest use found in Ephraim Chambers (?1680–1740), encyclopaedist. From parallelogram + -atic, perhaps after grammatic. Compare French parallélogrammatique.