Sawdust is the very small, powdery bits of wood that fall when a saw cuts. It is finer than chips or shavings — more like dust, which is why the second half of the word is dust. You smell it in a workshop; it sticks to clothes and gets in your hair. People sweep it up, use it to soak spills on a floor, put it in animal bedding, or (in older, cheaper packing) stuff it around breakable things. The word itself is ordinary and mostly stays literal. Though actually, when someone says food “tastes like sawdust,” they do not mean there is wood in it; they mean it is dry, dull, and no pleasure to chew.