• synonyms


[soh-uh s]
noun, plural pso·ai [soh-ahy] /ˈsoʊ aɪ/, pso·ae [soh-ee] /ˈsoʊ i/. Anatomy.
  1. either of two muscles, one on each side of the loin, extending internally from the sides of the spinal column to the upper end of the femur, which assist in flexing and rotating the thigh and flexing the trunk on the pelvis.
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Origin of psoas

1675–85; < New Latin < Greek psóās, accusative plural (taken as nominative singular) of psóa a muscle of the loins
Related formspso·at·ic [soh-at-ik] /soʊˈæt ɪk/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for psoas

Historical Examples of psoas

  • I had rather eat a sirloin of beef than know what they call the psoas muscle.

    The Man Who Laughs

    Victor Hugo

  • If the subjacent iliac and psoas muscles be implicated, the thigh is flexed upon the leg in decubitus.

  • In one pound weight of the psoas muscles Fleming counted no less than 300 Cysticerci.


    T. Spencer Cobbold

  • This boy died before he was 20, with a psoas abscess, and I remember crying myself to sleep the night I learned of his death.

  • Hyperæsthesia developed in more than one case in which injury to the psoas had led to hæmorrhage into the muscle sheath.

British Dictionary definitions for psoas


  1. either of two muscles of the loins that aid in flexing and rotating the thigh
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Word Origin for psoas

C17: from New Latin, from Greek psoai (pl)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for psoas


1680s, from Greek psoa (plural psoai) "muscles of the loins." Related: Psoitis.

Gk. [psoas], the gen. of the feminine noun [psoa], was mistaken by the French anatomist Jean Riolan (1577-1657) for the nom. of a (nonexistent) masculine noun. It was he who introduced this erroneous form into anatomy." [Klein]
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Online Etymology Dictionary, © 2010 Douglas Harper