the action or process of making something less in size, amount, or degree, or the state of being thus less;
e.g. He planned the reduction of the model's size so that it would be easier to transport. Since the reduction in their funding, they have had to find ways to spend less.
(noun)
something that has been made less in size, amount, or degree, or the amount by which it has been made less;
e.g. She made a significant reduction to the essay's length.