any of several large, green orthopteran insects (esp. family Tettigoniidae) having long, slender antennae and long hind legs: the male has highly developed stridulating organs on the forewings, that produce a shrill sound
echoic of the sound made by the males
See katydid in American Heritage Dictionary 4
Any of various green insects of the family Tettigoniidae related to the grasshoppers and the crickets, the male of which produces a shrill sound by rubbing together specialized organs on the forewings.