The word is always spelled with at least three As, though more are used when expressing an especially long or excited battlecry.
Much more complicated than it appears at first, Waaagh has multiple meanings for the greenskins of the warhammer universe.
1. It is the noun used to describe a warband of greenskins, the bigger the WAAAGH!, the more fiercely the greenskins fight.
2. WAAAGH! is also the description of the orcs spirituality and will to fight. When an orc (also spelled ork) possesses more WAAAGH! then his fellows he is usually bigger and stronger, or in the case of the goblins, more clever and agile, then the other greenskins. In any given WAAAGH! (Warband), the greenskin with the most WAAAGH! (Power) is declared Da Big Boss, and the other greenskins will follow him until he dies in combat, or is killed by a greenskin with more WAAAGH! than him.
The term WAAAGH! is always capitalized, must contain at least three A's, but can have as many as the user wishes, and is always followed by at least one exclamation point.