All 7 Uses

solemn
in
The Horse and His Boy
(Edited)

It was a musical noise, but so strong and solemn as to be a little frightening.
Chpt 4

solemn = very serious--possibly dignified
The light was too bad now for Shasta to see much of the cat except that it was big and very solemn.
Chpt 6
Its mane, and some strange and solemn perfume that hung about the mane, was all round him.
Chpt 11
The trumpets sounded again: a new noise to Shasta, not huge and solemn like the horns of Tashbaan nor gay and merry like King Lune's hunting horn, but clear and sharp and valiant.
Chpt 12
I must have your solemn and princely word...
Chpt 12 *

solemn = very serious
It was very solemn and very dreadful.
Chpt 13

solemn = very serious--possibly dignified
Both were still and solemn for a moment as each saw that the other knew about Aslan.
Chpt 14

Definitions:

(1) (solemn)
in a very serious (and often dignified) manner
(2) (meaning too rare to warrant focus)
Less commonly, solemn can mean that something was done with great or appropriate ceremony. It can also be used to describe something as dark or undecorated.