The term 'DISSOLVED OUT BY PERCOLATION' can be summarized as 'LEACHED', which is a 7-letter word. Leaching is a process in which a liquid, such as water, passes through a porous material, such as soil, and extracts soluble substances from it. This process is often used to remove contaminants from soil or to extract minerals from ore. In the case of dissolved out by percolation, the liquid is passing through the material and extracting the dissolved substances from it.