kẻ xâm nhập 
intruder, infiltrator [ kẻ ] : individual, single, person, man; to write (on a sign)
[ xâm ] : (1) to invade, usurp; (2) dizzy, giddy
[ nhập ] : to bring in, put in, import; to join, enter, add; to receive
Most Common Compounds Set 1:
Most Common Compounds Set 2 :