The term 'difficult to grasp' can be described by a variety of words, such as ELUSIVE (7 letters), EELY (4 letters), INTANGIBLE (10 letters), EELLIKE (7 letters), and SLIPPERY (8 letters). ELUSIVE refers to something that is hard to find or capture, while EELY implies something that is slimy or SLIPPERY. INTANGIBLE means something that cannot be touched or seen, and EELLIKE suggests something that is similar to an eel in terms of its shape or texture. Lastly, SLIPPERY implies something that is hard to hold onto or keep a grip on. All of these words together describe something that is difficult to understand or comprehend.