What does the term "metathesis" refer to in linguistics?

The term "metathesis" in linguistics specifically refers to the phenomenon where the order of sounds within a word is changed. This can occur naturally in language evolution or as a result of speech patterns among speakers. For example, the historical shift of the word "ask" being pronounced as "aks" showcases this sound reordering.

This concept highlights how language is fluid and can change over time, often influenced by colloquial usage or phonetic ease for the speaker. In contrast, the other options pertain to different linguistic processes, such as adding additional sounds, forming new words, or shifts in meaning, which do not align with the precise definition of metathesis.