For most of ancient China, chopsticks were called “箸zhù”(Evidence can be found in a large number of ancient documents), and Chinese neighbors learned this name. Later, due to some customs changes, Chinese people changed their chopsticks to “筷kuài”, while their Asian neighbors still used the old name箸. In some parts of China today, some dialects still call chopsticks 箸too.
Because the pronunciation of ” 箸zhù” is the same as “住zhù”, it is unlucky for people who make a living from water shipping（“住zhù” in Chinese means to STOP, which means that shipping activities may encounter trouble, or worse results – shipwrecks.）, so “箸” has become a taboo.
So these people gave chopsticks a new name ——“筷kuài”.
“筷kuài” is pronounced the same as “快kuài”， and “快” means FAST in Chinese. This indicates that people hope that shipping activities are safe and efficient.
This has affected the habits of other people, and people gradually refer to chopsticks as “筷”. This is an interesting example of language development.