名詞 melioration:

1. the act of relieving ills and changing for the better
   同義詞：amelioration, betterment
2. a condition superior to an earlier condition
   同義詞：improvement
3. the linguistic process in which over a period of time a word grows more positive in connotation or more elevated in meaning

mel.io.ra.tion

n.（名詞）

The act or process of improving something or the state of being improved.
改善：改進(jìn)某物的行動或過程或正在被改進(jìn)的狀態(tài)
An improvement.
改進(jìn)
The linguistic process by which a word over a period of time grows more elevated in meaning or more positive in connotation.
改良：在一段時期里一個字的語義逐漸提高及內(nèi)涵更明確的語言學(xué)過程