1) German invention 2) Ground-water separator 
A coffee filter is a coffee-brewing utensil, usually made of disposable paper. This enables it to trap the coffee grounds and allow the liquid coffee to flow through. Paper filters remove oily components called diterpenes; these organic compounds, present in unfiltered coffee are known to be antimicrobial and antiinflammatory. Metal or nylon mesh ...
[n] - filter (usually of paper) that passes the coffee and retains the coffee grounds
noun filter (usually of paper) that passes the coffee and retains the coffee grounds