Bot. shaped like a butterfly: said of certain flowers, esp. those of some legumes, as the pea
Origin of papilionaceousfrom Classical Latin papilio, butterfly ( from reduplicated, reduplication of Indo-European base an unverified form pel-, to fly, flutter, swim from source Old English fifealde, butterfly) + -aceous
Having a bilaterally symmetrical corolla somewhat resembling a butterfly, characteristic of certain plants of the pea family such as a sweet pea.
Origin of papilionaceousLatin pāpiliō pāpiliōn- butterfly ; see pavilion . -aceous