Other forms: runts
A runt is the smallest and weakest animal in a litter. The runt of the litter, a runt piglet, saved the runt.
It is a real farming and breeding term: the runt is at a disadvantage feeding and often needs hand-rearing to survive. The runt of the litter is the fixed phrase. Applied to a person it is an insult meaning small and insignificant, and it is a harsh one. Note that runts frequently catch up entirely, which is the whole reason the phrase is used hopefully as often as dismissively.
1nounruntThe smallest and weakest animal in a litter.
“Nobody wanted the runt, so we took the tiny puppy home ourselves.”
runt is a smallest offspring.
The OED classifies this word as "of unknown origin". Some see a connection to Middle Dutch runt (“ox”), but the OED considers this to be unlikely. Possibly connected to Icelandic hrotti meaning "brute".
Etymology from Wiktionary, CC BY-SA