cơ mật 
important and secret [ cơ ] : (1) foundation; (2) occasion, opportunity, circumstance; (3) odd; (4) regiment; (5) machine, mechanism, motor, engine; (6) airplane; (7) hunger, famine; (8) muscle; (9) outburst, crisis
[ mật ] : (1) honey, molasses; (2) gall, bile; (3) secret, confidential, classified; (4) dense, thick, close, intimate
Most Common Compounds Set 1:
Most Common Compounds Set 2 :
cơ mật viện security council