n pl but sing or pl in constr 1  :  the psychology of mental or emotional forces or processes developing esp. in early childhood and their effects on behavior and mental states  2  :  explanation or interpretation (as of behavior or mental states) in terms of mental or emotional forces or processes  3  :  motivational forces acting esp. at the unconscious level psy*cho*dy*nam*ic adj psy*cho*dy*nam*i*cal*ly adv 
 
   
 
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