Definitions of grim:

• adjective:   not to be placated or appeased or moved by entreaty

  Example: "Grim determination"

• adjective:   characterized by hopelessness; filled with gloom

  Example: "Took a grim view of the economy"

• adjective:   harshly ironic or sinister

  Example: "A grim joke"

• adjective:   shockingly repellent; inspiring horror

  Example: "The grim aftermath of the bombing"

• adjective:   harshly uninviting or formidable in manner or appearance

  Example: "A grim man loving duty more than humanity"

• adjective:   causing dejection

  Example: "Grim rainy weather"

• name:  A surname (rare: 1 in 50000 families; popularity rank in the U.S.: #5404)