taru-adjective, adverb taking the 'to' particle
uninteresting; dampening the mood; spoiling the fun
A yojijukugo describing something that is utterly uninteresting or that spoils the enjoyment of a situation. Often used in literary or formal contexts with たる or として.
His story was utterly uninteresting.
That joke threw a wet blanket on the gathering.
Everyday word for 'boring' or 'trivial'. 興味索然 is a much more formal, literary expression.
Verb meaning 'to be spoiled' or 'to lose interest', often used for a mood turning sour. 興味索然 describes the state or quality of being uninteresting or mood-dampening.
A yojijukugo composed of 興味 (interest) and 索然 (desolate, dreary). The exact historical derivation is uncertain, but the combination conveys a complete lack of interest or a mood-killing quality.