Smiling widely, showing your teeth in an expression of happiness, amusement, or sometimes nervousness.
From Old Norse 'grenja' meaning to gnash or grin. The word has meant showing teeth in a smile since medieval times.
When you grin at someone, your mirror neurons in their brain fire up too—literally making their face want to copy yours, which is why smiles are contagious and grins can brighten an entire room!
Complete word intelligence in one call. Free tier — 50 lookups/day.