Synecdoche is a rhetorical trope and a type of figurative speech similar to metonymy—a figure of speech in which a term that denotes one thing is used to refer to a related thing.[4][5] Indeed, synecdoche is sometimes considered a subclass of metonymy. It is more distantly related to other figures of speech, such as metaphor.[6]
More rigorously, metonymy and synecdoche can be considered sub-species of metaphor, intending metaphor as a type of conceptual substitution (as Quintilian does in Institutio oratoria Book VIII). In Lanham's Handlist of Rhetorical Terms,[7] the three terms have somewhat restrictive definitions, arguably in tune with a certain interpretation of their etymologies from Greek: