noun A paper or cardboard wrapper used to enclose small, flat items, especially letters, for mailing.
noun Something that envelops; a wrapping.
noun A bag containing the lifting gas of a balloon or airship; fabric that encloses the gas-bags of an airship.
noun A mathematical curve, surface, or higher-dimensional object that is the tangent to a given family of lines, curves, surfaces, or higher-dimensional objects.
noun A curve that bounds another curve or set of curves, as the modulation envelope of an amplitude-modulated carrier wave in electronics.
noun The shape of a sound, which may be controlled by a synthesizer or sampler.
noun The information used for routing a message that is transmitted with the message but not part of its contents.
noun An enclosing structure or cover, such as a membrane; a space between two membranes