Is metonymy considered to be linguistic or extralinguistic factor of semantic change? For example crown for a monarchy
Wikipedia lists "metonymy" under its types of semantic change:
A number of classification schemes have been suggested for semantic change. The most widely accepted scheme in the English-speaking academic world is from Bloomfield (1933):
- Narrowing: Change from superordinate level to subordinate level. For example, skyline formerly referred to any horizon, but now it has narrowed to a horizon decorated by skyscrapers.
- Widening: Change from subordinate level to superordinate level. There are many examples of specific brand names being used for the general product, such as with Kleenex. Such uses are known as generonyms.
- Metonymy: Change based on contiguity between concepts, e.g., horn "animal horn" → "musical instrument".
So yes, metonymy can be considered a factor of semantic change.