Well, in this case at least, 'envelope' comes directly from the French.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
DMWMany people (including me) pronounce it with an "en" sound; many others pronounce it with an "on" sound,That's right, and in the verb form — envelop— it has to be 'en', with the stress on the second syllable.