Metonymy, meronymy, and mereology represent distinct semantic and ontological concepts, distinguishing figures of substitution from part-whole lexical relations and formal philosophical theories.
The claim is specific, falsifiable, and supported by linguistics and ontology literature, which treats metonymy (a figure of speech/semantic shift), meronymy (part-whole lexical relation), and mereology (formal philosophical theory of parts and wholes) as distinct categories.