What's the noun for envelopment? Here's the word you're looking for.
envelope
A paper or cardboard wrapper used to enclose small, flat items, especially letters, for mailing.
Something that envelops; a wrapping.
A bag containing the lifting gas of a balloon or airship; fabric that encloses the gas-bags of an airship.
(geometry) A mathematical curve, surface, or higher-dimensional object that is the tangent to a given family of lines, curves, surfaces, or higher-dimensional objects.
(electronics) A curve that bounds another curve or set of curves, as the modulation envelope of an amplitude-modulated carrier wave in electronics.
(music) The shape of a sound, which may be controlled by a synthesizer or sampler.
(computing) The information used for routing a message that is transmitted with the message but not part of its contents.
(biology) An enclosing structure or cover, such as a membrane.
(engineering) The set of limitations within which a technological system can perform safely and effectively.
(astronomy) The nebulous covering of the head or nucleus of a comet; a coma.
An earthwork in the form of a single parapet or a small rampart, sometimes raised in the ditch and sometimes beyond it.
“Through such envelopments, a commander could create kessels and systematically destroy an encircled enemy force.”
“Suddenly, with flight, securing the flanks did not guarantee the security of the rear area, and though vertical envelopments took time to perfect, they were possible.”
