Meaning of the word solemnly in English

What does solemnly mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

solemnly

US /ˈsɑː.ləm.li/
UK /ˈsɒl.əm.li/

Adverb

seriously and without any humor:

Example:
I solemnly promise to tell the truth.