"Slack demand" refers to a situation where there is not enough interest or need for a product or service. It means that there is less demand than what is expected or necessary for the product to be successful. Full definition
The biggest markets in the West are shifting away from coal, and there's not a lot of slack demand for coal power; if anything, there's an excess of capacity. (vox.com)
Analysts have cited a number of reasons, such as slack demand for wide - body planes like Boeing's 777 and airlines waiting longer before replacing aging planes. (fortune.com)
It might seem unimportant to know exactly why copper has been added to the list of sick commodities, but if it is more than a fright over excess supply and slack demand then we could be on the verge of a rerun of the GFC. (businessnews.com.au)