The term 'Square PEG in a Round Hole' is an idiom used to describe someone or something that does not fit into their environment. It is often used to describe someone who is different or unique, and does not conform to the expectations of their peers. The crossword solution for this term is 'PEG', which is a three-letter word. A PEG is a cylindrical object with a flat head, which is used to fasten two objects together. In this case, it is used to represent someone or something that does not fit in.