The term 'smallest of the litter' can be described by two crossword solutions: 'RUNT' (4 letters) and 'RUNTS' (5 letters). A RUNT is an animal that is smaller than its siblings, usually due to a lack of nutrition or other health issues. RUNTS are often weaker and less likely to survive than their siblings. The term 'RUNTS' is used to describe a group of animals that are all smaller than their siblings. This term is often used to describe a litter of puppies or kittens that are all smaller than their siblings.