/i fem'euh rop"teuhr euhn/ , adj.
1. belonging or pertaining to the insect order Ephemeroptera, comprising the mayflies.
n.
2. ephemerid.
[ Ephemeropter ( a ) (equiv. to Gk ephémer ( on ) EPHEMERON + -o- -O- + -ptera, neut. pl. of -pteros -PTEROUS) + -AN ]