The thin protective covering or husk on the kernels of cereal grains such as barley and wheat. Though the Biblical references to chaff are figurative, they reflect the threshing practices common in ancient times. After harvesting, this inedible membrane covering of the valuable grain was useless, and hence was an appropriate symbol of something light, worthless, and undesirable, something to be separated from the good and to be disposed of.
First, the threshing operation broke the chaff loose from the kernel. Then by winnowing, the light chaffy part was carried away like dust in the wind. (See WINNOWING.) This well illustrates how Jehovah God both removes the apostates from among his people and also disposes of wicked persons and opposing nations. (Job 21:18; Ps 1:4; 35:5; Isa 17:13; 29:5; 41:15; Ho 13:3) God’s Kingdom will crush its enemies into such small particles that they will be easily blown away like the chaff.
The worthless chaff was often gathered and burned to prevent it from blowing back and contaminating the piles of grain. Similarly, John the Baptizer foretold the coming burning destruction of the wicked false religionists