Word Study
    psoas
WORDNET DICTIONARY
Noun psoas has 1 sense
CIDE DICTIONARY
psoas, n. [Gr.  a muscle of the loin: cf. f. psoas.]. 
                                            
                                         An internal muscle arising from the lumbar vertebræ and inserted into the femur. In man there are usually two on each side, and the larger one, or great psoas, forms a part of the iliopsoas.                                                                                 [1913 Webster]                                                                                                                    
                                                                                    OXFORD DICTIONARY
psoas, n.  either of two muscles used in flexing the hip joint.
                    Etymology
                        Gk, accus. pl. of psoa, taken as sing.
                                    
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