solemnly

Concise Oxford English Dictionary © 2008 Oxford University Press:
solemn/ˈsɒləm/

▶adjective

• 1 formal and dignified: a solemn procession.

• 2 not cheerful; serious.

• 3 deeply sincere.

– derivatives
solemnly adverb,
solemnness noun.

– origin ME (in the sense ‘associated with religious rites’): from OFr. solemne, from L. sollemnis ‘customary, celebrated at a fixed date’, from sollus ‘entire’.