Here's a breakdown of its etymology:
* Proto-Germanic: The earliest known form is *grimmaz*, meaning "fierce, angry, or savage."
* Old English: This evolved into *grim*, meaning "fierce, strong, harsh, or cruel."
* Middle English: The word continued to be used in similar senses.
* Modern English: The word took on its modern meaning, encompassing "unpleasant, harsh, or gloomy," as well as "determined, resolute, or unyielding."
So, the word "grim" originally referred to something fierce and aggressive, and has gradually evolved to cover a wider range of meanings, often associated with unpleasant or somber emotions.