The crossword solution for the term SOUR GRAPES CRITTER is FOX, which is a three letter word. The phrase 'sour grapes' is an idiom that means to be envious of something that one cannot have. A FOX is a small-to-medium sized omnivorous mammal belonging to several genera of the family Canidae. Foxes are known for their cunning and sly behavior, making them a fitting animal to represent the phrase 'sour grapes'.