quadral
Referring to four (or more) things; of, in or relating to the quadral grammatical number.
[…] in Konomala, Patpatar, Tolai, Kandas, Duke of York and Siar of New Ireland, these quadral forms have replaced the original plurals.
Of or relating to quadral polynomials.
Where it comes from
From New Latin quadrālis, from quadru- (“four-”) + -ālis.
Adapted from the Wiktionary entry quadral (CC BY-SA 4.0).