specter, ghost, haunting spirit
"The king's grim expression signaled that his anger had reached a boiling point."
Anger, wrath.
In plain English: A grim face is an expression that looks very serious and unhappy, often showing sadness or anger without smiling.
"He stared in grim silence at the bad news he had just received."
To make grim; to give a stern or forbidding aspect to.
"The dark clouds gathered above, grimming the horizon with an ominous threat."
In plain English: To grim is to make your face look very serious and unhappy by tightening your lips into a hard line.
"The old man grimaced in pain when he tried to lift his heavy box."
not to be placated or appeased or moved by entreaty
"grim determination"
"grim necessity"
"Russia's final hour, it seemed, approached with inexorable certainty"
"relentless persecution"
"the stern demands of parenthood"
shockingly repellent; inspiring horror
"ghastly wounds"
"the grim aftermath of the bombing"
"the grim task of burying the victims"
"a grisly murder"
"gruesome evidence of human sacrifice"
"macabre tales of war and plague in the Middle ages"
"macabre tortures conceived by madmen"
harshly uninviting or formidable in manner or appearance
"a dour, self-sacrificing life"
"a forbidding scowl"
"a grim man loving duty more than humanity"
"undoubtedly the grimmest part of him was his iron claw"
filled with melancholy and despondency
"gloomy at the thought of what he had to face"
"gloomy predictions"
"a gloomy silence"
"took a grim view of the economy"
"the darkening mood"
"lonely and blue in a strange city"
"depressed by the loss of his job"
"a dispirited and resigned expression on her face"
"downcast after his defeat"
"feeling discouraged and downhearted"
dismal and gloomy, cold and forbidding
"The grim wind howled through the empty street, making the old stone building feel cold and forbidding."
In plain English: Grim means looking very sad and serious, often because of something bad that has happened.
"The news was grim, but we had to face reality and do our best."
Usage: Avoid using "grim" as a synonym for "sad" when you intend to convey something specifically bleak, forbidding, or devoid of hope. In formal writing, prefer "dismal" or "forbidding" over the more colloquial "grim" to maintain a precise tone.
An English surname
"The Grim family has lived in the village for three generations."
The word "grim" comes from the Old English term for a fierce or angry expression. It ultimately traces back to an ancient root meaning to resound like thunder or grumble.