nonplushed

Adjective

nonplussed (comparative more nonplussed, superlative most nonplussed)

1. Unsure how to act or respond; bewildered, perplexed.
   • [N]ote the honeſt Quaker vvas nonpluſſed, and greatly ſurprized at that Queſtion.1724, [Daniel Defoe], The Fortunate Mistress; […] [Roxana], London: […] E. Applebee, […], published 1740, →OCLC, page 277

   Synonyms:

   confounded, vexed, lost for words, addle-pated, addled, addlepated, at a loss, at a loss for words, at sea, at sixes and sevens

   Antonyms:

   plussed

2. (US, informal, nonstandard) Unaffected, unfazed; unimpressed.
   • "I regard Dean [W. P.] Baddeley's gambling activities with embarrassment and dismay," said Anglican dean of Melbourne S. Barton Babbage. […] The Rev. Baddeley remained nonplussed. "I don't intend to make a habit of going to the races but I feel clergymen should mix as our Lord did with all walks of...1960 August 2, “Cleric’s error was to win his wagers”, in Oakland Tribune, home edition, volume CLXXIII, number 33, Oakland, Calif.: Oakland Tribune, →ISSN, →OCLC, page E7, column 6

   Synonyms:

   blasé, jaded, adiaphroistic, apathetic, apathistical, blithe, deaf, cool, shiftless, dispassionate

   Antonyms:

   plussed