What is the term for a type of semantic shift where words acquire negative or pejorative connotations?

The term for a type of semantic shift where words acquire negative or pejorative connotations is known as deterioration. This process involves a shift in meaning that results in a more negative or less favorable interpretation of a word over time. For example, the word "silly" originally meant happy or fortunate, but over time has come to imply foolishness or a lack of seriousness.

In contrast, elevation refers to a semantic shift where words take on more positive or favorable meanings. Ellipsis is a linguistic term related to the omission of words in a sentence, and diphthong pertains to a specific type of vowel sound in phonetics rather than semantic change. Therefore, understanding deterioration helps clarify how language evolves and reflects social attitudes, particularly in terms of the connotations associated with particular words.