taru-adjective, adverb taking the 'to' particle
solemnly; quietly; in a dignified silence
Describes a solemn, dignified, and quiet atmosphere or manner, often used in formal or ceremonial contexts. Functions as a taru-adjective or adverb with と.
式典は粛々と執り行われた。
The ceremony was conducted solemnly.
会場は粛々とした雰囲気に包まれていた。
The venue was enveloped in a solemn atmosphere.
静か is a general word for 'quiet' or 'silent', while 粛々 carries a nuance of dignified, formal solemnity.
厳か also means 'solemn' or 'awe-inspiring', but is a na-adjective, whereas 粛々 is a taru-adjective used in more literary or formal registers.
Reduplication of 粛 (しゅく), meaning 'solemn' or 'quiet', forming a taru-adjective. The exact historical derivation is uncertain, but the form follows a classical pattern for creating adjectival adverbs.