nub 
/ˈnʌb/ noun
plural nubs /ˈnʌb/ noun [count] : a small piece or end
▪ The dog chewed his bone down to a nub. : a small part that sticks out ▪ The shoes have little nubs on the bottom that prevent you from slipping.
▪ The dog chewed his bone down to a nub. : a small part that sticks out ▪ The shoes have little nubs on the bottom that prevent you from slipping.
the nub
: the main part or point of something
▪ the nub of the story/problem/matter/argument
▪ the nub of the story/problem/matter/argument
