To be so shocked or stunned that one's eyes are wide open and tongue is tied, unable to say a word.
瞪瞪着眼；结舌说不出话来。瞪着眼睛说不出话来。形容窘困或惊呆的样子。
清·霁园主人《夜谭随录·梨花》因耳语其故，公子大骇，入舱隐叩细君，细君结舌瞠目。”
When he saw the magician's final trick, he stood there, stunned and staring, completely speechless.
Learn the next connected idiom: 瞠目结舌 (chēng mù jié shé) → 舌战群儒 (shé zhàn qún rú)
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