đau đớn vô cùng 
unending suffering [ đau ] : pain; painful, ill
[ đớn ] : broken
[ vô ] : (1) in-, im-, (negative prefix); (2) in, at, on; (3) to go into, enter [= vào]
[ cùng ] : same, together; to act together (with), and; to follow
Most Common Compounds Set 1:
Most Common Compounds Set 2 :