speechless

Etymology

From Middle English specheles, from Old English sprǣċlēas (“speechless; without the power of speak”), from Proto-Germanic *sprēkalausaz, equivalent to speech + -less. Cognate with West Frisian sprakeleas (“speechless”), Dutch sprakeloos (“speechless”), German Low German spraaklos (“speechless”), German sprachlos (“speechless”).

adj

1. Not speaking; not knowing what to say; silent, especially due to surprise, amazement, etc.
   When he walked into his surprise birthday party, he was completely speechless.
   The attack was so unwarranted and delivered with such venom that his unpreparedness for it left him speechless. 1966, James Workman, The Mad Emperor, Melbourne, Sydney: Scripts, page 62
2. (archaic) Synonym of unspeakable.
   Immortal Pleaſures round my ſwimming Eyes did dance, And ſpeechleſs Joys, in whoſe ſweet Tumult toſt, I thought my Breath, and my new Being loſt. 1690, John Dryden, The State of Innocence, and Fall of Man, J.M., page 14
   O Mother Earth, O Sun that makest clean, What poison have I heard, what speechless sin ! 1902, Gilbert Murray, Euripides, Longmans, Green, and co., page 32