窮(きゅう)するto be at a loss, to be puzzled, to be perplexed, to be at one's wit's end, to be in a dilemma, to not know what to (do, say, etc)

Definiciones del Diccionario

Verbo する (Tipo especial), Verbo intransitivo
1. 1.
  EN to be at a loss, to be puzzled, to be perplexed, to be at one's wit's end, to be in a dilemma, to not know what to (do, say, etc)
2. 2.
  EN to be pressed for, to be pinched for, to become poor, to be reduced to poverty