1.Definition: causing dejection
"Grim rainy weather"
2.Definition: filled with melancholy and despondency
"Took a grim view of the economy"
3.Definition: harshly ironic or sinister
"A grim joke", "Grim laughter"
4.Definition: harshly uninviting or formidable in manner or appearance
"A grim man loving duty more than humanity", "Undoubtedly the grimmest part of him was his iron claw"
5.Definition: not to be placated or appeased or moved by entreaty
"Grim determination", "Grim necessity"
6.Definition: shockingly repellent; inspiring horror
"The grim aftermath of the bombing", "The grim task of burying the victims"