быть неспособным сказать/сделать что-л. The shock was so great that for a moment I was at a loss for words. We were at a loss to know what to do when the jewels were stolen.
BE AT A LOSS
Англо-русский перевод BE AT A LOSS
English-Russian Muller's dictionary 24 edition. Англо-Русский словарь Мюллера 24 редакция. 2012