False 9
A False 9 is an unconventional attacking player (a striker or centre forward), who drops deep into midfield in order to make opposing defenders (usually centre backs) either mark him or cover up the space he created behind him, so the false 9 can make more space on the front line for his teammates or himself for scoring.
A false 9 is good at dribbling to take advantage of space between the lines, at short passing to link up with the midfield and vision to play through teammates making runs from deep to goal.
The term false 9 comes from the traditional number for CF players (number nine), and the fact that normally a centre forward traditionally stayed near the line of defenders until they got an opportunity to move past them toward goal.