A form of metaphor in which there is a substitution of a word referring to an attribute for the thing that is meant. Unlike a metaphor, however, which is derived from similarity, metonymy is based on contiguity (as is a synecdoche). Examples of a metonymical substitution for the real thing are “Survey research involves counting heads” and “Psychology conferences are all about talking heads” (instead of people in both cases). The danger with metonymy is that it can lead to excesses in typological thinking.
See Metaphor, Synecdoche, Tropes, Typological thinking