envelop
Pronunciation: /ɪnˈvɛləp, ɛn-/
verb ( envelops, enveloping, enveloped)
Origin:
late Middle English (formerly also as invelop(e)): from Old French envoluper, from en- 'in' + a second element (also found in develop) of unknown origin
Envelop is a verb, stressed on the second syllable and meaning ‘wrap completely’. The noun meaning ‘paper container for a letter’ is envelope, stressed on the first syllable.
Do not confuse envelop with envelope. Envelop means 'cover or surround something completely' ( the mist seemed to envelop the boat), whereas envelope means 'a paper container for a letter' ( a stamped addressed envelope).