The term MARSH CRITTER is a crossword solution that can be broken down into two words: 'CROC' (4 letters) and 'MARSH'. CROC is a shortened form of the word crocodile, which is a large reptile found in tropical regions. MARSH is an area of wetland, usually near a river or lake, that is characterized by soft, muddy ground and tall grasses. Therefore, MARSH CRITTER can be defined as any type of animal that lives in a marshy environment, such as a crocodile.