Obsolete (adj., v.), obsolescent (adj.)

Obsolete 可當形容詞和動詞用,而 obsolescent 只當形容詞用。當形容詞用時,obsolete 意為「已廢棄 (不用) 的,已淘汰的,已完全過時的」,如 No one uses these words anymore; they’re obsolete. (現在沒有人再用這些字;它們已廢棄不用了);Gas lamps became obsolete when electric lighting was invented. (電燈發明之後煤氣燈就被淘汰了);obsolete ideas/machinery (過時的思想/機器)。

Obsolescent 意為「逐漸被廢棄 (不用) 的,逐漸被淘汰的,逐漸過時的」,如 This type of computer is obsolescent. (這種電腦逐漸被淘汰);Going abroad to study for a PhD degree is obsolescent. (到國外唸博士學位逐漸退流行);Much of our existing electrical equipment is obsolescent. (我們現有的許多電氣設備逐漸被淘汰)。