The word "grin" refers to a facial expression that involves smiling broadly, where the mouth is open and the teeth may be visible. It often conveys happiness, amusement, or even a playful demeanor. A grin can also suggest a sense of mischief or joy.
The word "grin" comes from the Old English word "grinnan," which means "to snarl" or "to show the teeth." It has Germanic roots, and similar words can be found in various Germanic languages, such as the Old Norse "grina" (to grin) and the Middle Dutch "grijnen" (to show the teeth).