ngoan cố 
stubborn, obstinate, contumacious [ ngoan ] : nice, sweet, well-mannered, well-behaved, obedient
[ cố ] : (1) to make an effort, try (very hard); (2) great grandfather; (3) to pawn; (4) reason; (5) old, former, late (deceased); (6) intentional, premeditated; (7) firm, strong; (8) innate, original; (9) to look after, care for, turn one’s head
Most Common Compounds Set 1:
Most Common Compounds Set 2 :