mook. 1  Seems to be a New York City synonym for hood or crook.. 2  Baltimore MD Used on Homicide; Life on the streets by Detective Lewis. 3  An insignificant, contemptible person--usually male.  an insignificant or contemptible 1  person. A large, clumsy person; 2  oaf. an oaf, a loud boor, a witlessly enthusiastic fan of insignificant things or events.