a.  1.  Eight and one more; one less than ten;
 
n.  1.  The number greater than eight by a unit; nine units or objects.  
2.  A symbol representing nine units, as 9 or ix.  
3.  A group of nine people;

Noun  1.  nine  the cardinal number that is the sum of eight and one 
2.  nine  a team of professional baseball players who play and travel together; "each club played six home games with teams in its own division"  
Adj.  1.  nine  denoting a quantity consisting of one more than eight and one less than ten 