The word according to the dictionary

English

WOTD – 6 May 2025

Etymology

PIE word
*né

From Late Middle English imperturbable (“undisturbed; impossible to disturb”), borrowed from Late Latin imperturbābilis, from Latin im- (variant of in- (prefix meaning ‘not’)) + Late Latin perturbabilis (“perturbable”) (from Latin perturbō (“to confuse; to alarm, disturb, trouble, perturb”) + -bilis (suffix forming adjectives denoting a capacity or worth of being acted upon)). Perturbō is derived from per- (intensifying prefix) + turbō (“to agitate, disturb, unsettle, perturb; to upset”) (from turba (“disorder, disturbance, turmoil”) (possibly from Ancient Greek τῠ́ρβη (tŭ́rbē, “confusion, disorder, tumult”), either from Pre-Greek, or Proto-Indo-European *(s)twerH- (“to agitate, stir up; to urge on, propel”)) + -ō (suffix forming infinitives of regular first-conjugation verbs)). By surface analysis, im- (prefix meaning ‘not’) +‎ perturbable.

Pronunciation

(Received Pronunciation) IPA^(key): /ˌɪmpəˈtɜːbəbl̩/
(General American) IPA^(key): /ˌɪmpəɹˈtɜɹbəb(ə)l/
Audio (General American): (file)
Hyphenation: im‧per‧tur‧ba‧ble

Adjective

imperturbable (comparative more imperturbable, superlative most imperturbable)

Not capable of being, or not easily, perturbed, excited, or upset; calm and collected, even under pressure.
Synonyms: cool-headed, unexcitable, unperturbable; see also Thesaurus:calm, Thesaurus:temperate

Antonyms: perturbable; see also Thesaurus:irritable, Thesaurus:nervous
- 1605, Giacomo Affinati d’Acuto Romano, chapter 23, in A M, transl., The Dumbe Divine Speaker, or: Dumbe Speaker of Diuinity. , London: ">…] for William Leake, , →OCLC, page 257:
  o a vviſe man there can happen no iniury or offence at all, to moleſt the felicity of his minde, vvhich (in the Stoicks opinion) ought to bee imperturbable, and his heart adamantine.
- 1815 February 24, , chapter VIII, in Guy Mannering; or, The Astrologer. In Three Volumes.">…], volume I, Edinburgh: James Ballantyne and Co. for Longman, Hurst, Rees, Orme, and Brown, ; and Archibald Constable and Co., , →OCLC, page 116:
  he good Dominie bore all his disasters with gravity and serenity equally imperturbable. "Prodi-gi-ous!" was the only ejaculation they ever extorted from the much-enduring man.
- 1820 March, , chapter II, in The Monastery. A Romance. In Three Volumes.">…], volume II, Edinburgh: Longman, Hurst, Rees, Orme, and Brown, ; and for Archibald Constable and Co., and John Ballantyne, , →OCLC, pages 60–61:
  In the meanwhile, Sir Piercie Shafton sate still as a stone on the chair in which he had deposited himself, his eyes cast up to the ceiling as if he had meant to count every mesh of cobweb with which the arched roof was canopied, wearing at the same time a face of as solemn and imperturbable gravity, as if his existence had depended on the accuracy of his calculation.
- 1837, L E L, “Poverty”, in Ethel Churchill: Or, The Two Brides. In Three Volumes.">…], volume III, London: Henry Colburn, , →OCLC, page 280:
  "We may keep it by us," replied the pawnbroker, "for months; there is no demand for such articles." "But," exclaimed she, eagerly, "I shall soon redeem it!" "So you all say," returned the man, with imperturbable coolness.
- 1962 August, G Freeman Allen, “Traffic Control on the Great Northern Line”, in Modern Railways, Shepperton, Surrey: Ian Allan Publishing, →ISSN, →OCLC, page 132:
  This sort of thing is meat and drink to the born Controller—and Controllers are born with the right imperturbable temperament for the job; hence the fact that they are recruited from many different grades of operating staff, and some recruits don't stay the course.