Key terms in Language Change

Amelioration: Where a word takes on a more pleasant meaning, such as "brave" used to mean uncivilised.

Pejoration: Where a word takes on a less pleasant meaning e.g. "juvenile" was more associated with youth, whereas nowadays it is connected to imaturity

Semantic broadening: When a word's meanings grow in number.

Semantic narrowing: Where a word's meanings are reduced in number.