chaff (n.)

"husks of wheat, oats, or other grains," Old English ceaf "chaff," probably from Proto-Germanic *kaf- "to gnaw, chew" (source also of Middle Dutch and Dutch kaf, German Kaff), from PIE root *gep(h)- "jaw, mouth" (see jowl (n.1)). Used figuratively for "worthless material" from late 14c.