From Longman Dictionary of Contemporary Englishsolemnsol‧emn /ˈsɒləm $ ˈsɑː-/ ●○○ adjective 🔊 🔊 1SERIOUS PERSONvery serious and not happy, for example because something bad has happened or because you are at an important occasion 🔊 a solemn expression 🔊 Their faces suddenly grew solemn. 🔊 a solemn procession of mourners► see thesaurus at serious2PROMISEa solemnpromise is one that is made very seriously and with no intention of breaking it 🔊 a solemn vow 🔊 I’ll never be unfaithful again. I give you my solemn word.3SERIOUS PERSONperformed in a very serious waysolemn ritual/ceremony —solemnly adverb
Examples from the Corpus
solemn• Hence peace-makings were solemn and formal occasions, committing groups of people to restraint.• His movements were solemn and precise.• It was simple and quaint and the terrain around them was solemn and rugged.• solemnmusic• As the child subjected him to a solemn, no-nonsenseappraisal, Ashley's heart began to hammerbehind her ribs.• The occasion was a solemn one, and he wondered a little nervously how she would carry it off.• At that point, the solemn political discussion between Eleanor and young Joe ended abruptly, and Eleanor hurried off to bed.• Everyone stood respectfully, and looked solemn throughout the funeral service.• The judgeread the verdict in a clear and solemnvoice.solemn word• All I gave was my solemn word.• I gave her my most solemn word of honor that I loved her.• What fine, solemn words these are!From Longman Business Dictionarysolemnsol‧emn /ˈsɒləmˈsɑː-/ adjective1solemn and bindingLAW an agreement that is solemn and binding is recognized in lawOnly on the basis of a solemn and binding undertaking did they allow the purchase to proceed.2solemn oath/promise/pledge etc a promise that is made very seriously and with no intention of breaking itHe gave his testimony under solemn oath.The President had betrayed a solemn pledge.