The word "whittle" generally means to carve or shape something, typically wood, by repeatedly cutting away thin pieces from it. It can also refer to reducing something gradually in size, amount, or importance. For example, if you have a large task and you manage to break it down into smaller parts or eliminate unnecessary steps, you are "whittling" it down.
The word "whittle" comes from the Middle English "whittlen," which is derived from the Old English "hwit" meaning "white." It originally referred to removing the surface of something to reveal a lighter-colored material beneath.