taru-adjective, adverb taking the 'to' particle
eminent; prominent; distinguished; leading
Describes people or things that stand out as excellent or top-class. Often used in the pattern そうそうたる + noun, meaning 'a distinguished/illustrious group of ...'.
会場にはそうそうたる顔ぶれがそろった。
The venue was filled with a distinguished lineup of people.
彼はそうそうたる学者の一人だ。
He is one of the leading scholars.
taru-adjective, adverb taking the 'to' particle
ringing (of metal); resonant (of a musical instrument)
Literary or formal term for a clear, resonant metallic sound. Rare in modern everyday speech; more common in written descriptions.
鐘の音がそうそうと響き渡った。
The sound of the bell rang out resonantly.
著名 is a more common and neutral word for 'famous' or 'well-known', while そうそう is more formal and emphasizes being top-class or illustrious.
立派 means 'splendid' or 'fine' and is used more broadly for things of good quality or admirable character, whereas そうそう is specifically about being eminent or distinguished among peers.
Derived from the reduplication of 錚 (sō), a character meaning 'sound of metal'. The 'eminent' sense likely developed from the idea of something that rings out clearly and stands out. The exact historical derivation is uncertain.