taru-adjective, adverb taking the 'to' particle
Obsolete literary term describing a deeply sorrowful or melancholy state. Used in classical Japanese texts as a taru-adjective or adverb with と.
古い和歌に「悒々として暮らす」という表現が見られる。
In old waka poetry, one finds the expression 'living in melancholy'.
The exact derivation is uncertain. The kanji 悒 means 'sorrowful' or 'melancholy', and the reduplicated form 悒々 intensifies the meaning. The reading ゆうゆう is the on'yomi of the kanji.