The term 'slowly permeating' can be summarized by the crossword solution of 'osmotic, ' which refers to the process of diffusion through a semipermeable membrane. Osmosis is a type of passive transport, meaning that it does not require energy to move molecules from one side of the membrane to the other. This process is often used in biology to describe the movement of water molecules across a cell membrane. In general, osmosis occurs when there is a difference in concentration between two solutions on either side of a semipermeable membrane, and the molecules will move from the area of higher concentration to the area of lower concentration.