introvert

Etymology

From New Latin intrōvertere, from intro- (“within”) and vertere (“to turn”). Popularized as a psychological term by the German works of Carl Jung.

noun

1. (zoology) An organ or other body part that is or can be turned inside out, especially an anterior portion of some annelid worms capable of retraction.
   Important distinctions which obtain amongst the various ‘introverts’ or intro- and e-versible tubes so frequently met with in animal bodies. 1883, E. Ray Lankester, Encyclopaedia Britannica, Vol. XVI, p. 652, s.v. "Mollusca"
   Peanut worms (phylum Sipunculida) are drab-colored bottom dwellers, most of which are less then four inches long. Their body is divided into two sections: the trunk and the introvert. The introvert, the narrow neck-like anterior section, is used as a probe. 1990, Deborah A. Coulombe, Seaside Naturalist, page 76
   When a peanut worm feeds, it extends and waves its introvert so that the mouth at the tip wanders across the seabed. 2006, Nematodes, Leeches, and Other Worms, page 38
   The introvert is everted by hydraulic pressure exerted by contraction of body muscles on the coelomic fluid. 2009, Lynn Marguli, Michael J Chapman, Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth
2. (psychology) An introverted person: one who is considered more thoughtful than social, with a personality more inwardly than outwardly directed; one who often prefers to have time in non-social situations.
   An Extravert can hardly conceive the necessity which compels the Introvert to conquer the world by means of a system. 1916, Constance Ellen Long trans. Carl Jung as Collected Papers on Analytical Psychology, p. 349
   In order to understand the marked contract between Comte's mental attitude during his early years and that of his later life, we must keep in mind Jung's hypothesis of the two psychological types, the introvert and extrovert,—the thinking type and the feeling type. 1918 April, Phyllis Blanchard, “A Psycho-Analytic Study of August Comte”, in American Journal of Psychology, page 163
   All works of the imagination are conceived by men of the introvert type. May 21 1920, Challenge, page 44
   The introvert abstracts from the object and deals with it by concepts concentrating upon the inner world of thought. 1925, Charles Fox, Educational Psychology, page 254
   This softly spoken but fluent communicator describes himself as an introvert who prefers not to shout from the rooftops. January 13 2021, Paul Clifton, “Delivering a basis for rail changes”, in RAIL, issue 922, page 30
3. (figurative, proscribed) A reserved person.

adj

1. Alternative form of introverted.
   They were noticeably more introvert, schizoid and desurgent in temperament. 1934 July, British Journal of Psychology, page 26

verb

1. To turn inwards.
   1. To think about internal or spiritual matters.
      […] the Soul being straight, introverted […] into itself, and easily conforming to God's will and time […] 1671, Abraham Woodhead trans. The Life of the Holy Mother Saint Teresa..., xxviii
      The less we look abroad, the more our ideas are introverted, and our habitual impressions... grow together into a kind of concrete substance. 1822, William Hazlitt, “Prejudice”, in Table-talk, page 85
   2. (zoology) To withdraw an organ or body part within itself or its base.
      His awkward gait, his introverted toes, Bent knees, round shoulders, and dejected looks […] 1785, William Cowper, "The Task", Cant. IV, ll. 633 ff.