What does the name "combine harvester" mean?

The name "combine harvester" comes from the fact that it combines several harvesting operations into a single process. 

The machine can harvest, thresh, and clean crops such as wheat, corn, soybeans, and rice in a single operation. 

The term "combine" refers to the combination of the three major harvesting operations – reaping, threshing, and winnowing – that were traditionally done separately using different machines. 

The combine harvester was developed to increase efficiency and productivity in agriculture by performing all these operations in a single pass.