The term 'soak up like a sponge' can be summarized by the crossword solution 'ABSORB, ' which is a 6-letter word. To ABSORB means to take in or soak up something, such as liquid or energy. This phrase is often used to describe the ability of a sponge to take in large amounts of liquid. It can also be used figuratively to describe someone who is able to take in and understand a lot of information quickly.