whilst or while?
The forms whilst, amidst and amongst, unbeknownst all hark back to an older form of English that sounds overly formal and stilted in today's usage. Few people say 'hither' and 'thither' like they did not so long ago; we say 'here and there'. We say you not thou, so why oh why art thou still using whilst?
Using -st forms like these are still popular – championed, even – in pretentious language. The more modern forms are while, among, amid and unbeknown. It is much easier to say "amid the confusion" than "amidst the confusion".
Take note, too, that the -st forms are rarely encountered in American English, no matter how much they are loved by a minority few in Britain. Use superfluous -st endings by all means, if you really want to, but there is absolutely no need for you to use them – nor obligation, so don't let anyone bully you into thinking so.
About the author
Jesse Karjalainen is the author of The Joy of English: 100 conversations about the English Language, Cannibal – the language and history of the discovery of the New World, and Roanoke – the language and history of Early Colonial America.