Synecdoche is a figure of speech in which a part is used for the whole (as hand for sailor), the whole for a part (as the law for police officer), the specific for the general (as cutthroat for assassin), the general for the specific (as thief for pickpocket), or the material for the thing made from it (as steel for sword). You can find a fuller explanation here. The word also occurs in the title of a current...

A police officer is being investigated over claims he sent saucy text messages to a woman he had interviewed including one asking: "Do you want to see my truncheon?" The PC is to be quizzed by bosses after 18-year-old Megan Walton, of Southey Green, Sheffield, reported him for sending her a series of sexually-suggestive text messages to her mobile. He had taken her number when he interviewed the mum-of-one over a disturbance outside her house.The officer – who Megan said was old enough to be her father – first met her when he was doing house-to-house enquiries on Southey Green Road over a disturbance on the street. He called at her house with a female officer to ask Megan whether she had witnessed anything and while he was taking a statement from her he asked for her telephone number...