The term 'LITTERS' Least' is a reference to the smallest members of a litter of animals, often referred to as RUNTS. The term 'RUNT' is derived from the Old English word 'RUNT, ' which means 'smallest in size or weakest in strength.' RUNTS are usually the last to be born and the smallest of their littermates. They are often weaker and more vulnerable than their siblings, and may require extra care and attention in order to survive.