What is the translation express (adjective meaning fast) in Chinese? I want to know the translation of the word "express" (both characters and pinyin) as you would describe an express courier service? 
Also, is there a new-invented word (maybe by the youth) that is used today to convey the meaning of express?
'Express courier service' in Chinese is

速遞服務  or 快遞服務 

速遞/快遞 is shortened from '快速遞送/ 快速傳遞' (express delivery) . It can functions as an adjectival noun as in   速遞服務(express delivery service); 速遞文件(express delivery document)