kerblangFrench e, è, é, ê, ë – what's the difference?
https://jakubmarian.com/french-e-e-e-e-e-whats-the-difference/
>Ê with the circumflex accent marks an “e” after which originally some other letter was written (usually an S), but this letter is no longer present in its modern spelling.
[snip]
>By imagining “es” instead of “ê”, we can often deduce the meaning of unknown words; for example, forêt = forest, fête = “feste” = fest(ival); intérêt = interest and many others. The circumflex accent is used in the very same sense also for other vowels, for example île = isle, hôte = “hoste” = host, hâte = haste.
I will always remember this, thanks to my high school French teacher who, knowing her audience, gave us a few examples like "hôpital," and then said "So you can probably guess was 'bâtard' means..."
I had that "a-ha" moment not at first by learning that "fenêtre" means "window", but later when I learned the German word is "Fenster".