...there was a solemn promise that neither side would use Magic.
These were very solemn faces.
At any rate, when they had both put on their greens and come back to the edge of the water, and taken hands again, they were certainly a good deal more cheerful and less solemn than they had been the first time.
Digory’s heart beat wildly; he knew something very solemn was going to be done.
He went in very solemnly, looking about him.
Digory knew that he couldn’t possibly break in on so solemn a meeting, but there was no need to do so.
Everyone was staring solemnly at the Tree when Aslan suddenly swung round his head (scattering golden gleams of light from his mane as he did so) and fixed his large eyes on the children.
Then everyone cheered or bayed or neighed or trumpeted or clapped its wings and the royal pair stood looking solemn and a little shy, but all the nobler for their shyness.