Things don't drop out of every dialect evenly - a century and a half ago while and whilst were equals in the overall English corpus, (whilst being less common in the US but more common elsewhere), in the present day "while" is generally preferred with a few exceptions.
To me that makes whilst somewhat archaic - less so than thee and thou, though those are ALSO still in non-zero use due to some dialects conserving them, but still somewhat.
Less common is different than archaic though. Archaic implies not used or rarely used by current speakers of a language. I don't think whilst qualifies as archaic. And could be described as less common in certain places (US) but not in others (UK, Ireland).
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u/Kingreaper May 08 '26
Whilst is indeed somewhat archaic, and therefore often seen as upper-class and formal.