Bot. shaped like a butterfly: said of certain flowers, esp. those of some legumes, as the pea
Origin of papilionaceous; from 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 papili&omacron;, papili&omacron;n-, butterfly; see pavilion + –aceous.