意余って言葉足らず
Meanings
1
at a loss for words; unable to express oneself adequately
Describes a state where one's feelings or intentions are too strong or complex to be put into words, resulting in insufficient or clumsy expression. Often used when emotions overwhelm the ability to speak clearly.
My gratitude was so strong that I was at a loss for words.
He was so nervous that he could only give a clumsy, inadequate reply.