Why is the ninth month called September?
"husks," Old English ceaf "chaff," probably from Proto-Germanic *kaf- "to gnaw, chew" (cf. 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.
the refuse of winnowed corn. It was usually burned (Ex. 15:7; Isa. 5:24; Matt. 3:12). This word sometimes, however, means dried grass or hay (Isa. 5:24; 33:11). Chaff is used as a figure of abortive wickedness (Ps. 1:4; Matt. 3:12). False doctrines are also called chaff (Jer. 23:28), or more correctly rendered "chopped straw." The destruction of the wicked, and their powerlessness, are likened to the carrying away of chaff by the wind (Isa. 17:13; Hos. 13:3; Zeph. 2:2).