You manipulate others into doing your bidding using threats. Unlike Deception or Diplomacy, Intimidation is typically a blunt instrument with little room for nuance or care.
Coerce. With threats either veiled or overt, you attempt to bully a creature into doing what you want.
Demoralize. With a sudden shout, a well-timed taunt, or a cutting putdown, you can shake an enemy's resolve.