envelopes

/EH1 N V AH0 L OW0 P S/
noun
  1. 1

    A paper or cardboard wrapper used to enclose small, flat items, especially letters, for mailing.

  2. 2

    Something that envelops; a wrapping.

  3. 3

    A bag containing the lifting gas of a balloon or airship; fabric that encloses the gas-bags of an airship.

  4. 4

    A mathematical curve, surface, or higher-dimensional object that is the tangent to a given family of lines, curves, surfaces, or higher-dimensional objects.

  5. 5

    A curve that bounds another curve or set of curves, as the modulation envelope of an amplitude-modulated carrier wave in electronics.

  6. 6

    The shape of a sound, which may be controlled by a synthesizer or sampler.

  7. 7

    The information used for routing a message that is transmitted with the message but not part of its contents.

  8. 8

    An enclosing structure or cover, such as a membrane; a space between two membranes

  9. 9

    The set of limitations within which a technological system can perform safely and effectively.

  10. 10

    The nebulous covering of the head or nucleus of a comet; a coma.

  11. 11

    An earthwork in the form of a single parapet or a small rampart, sometimes raised in the ditch and sometimes beyond it.

Source: https://en.wiktionary.org/wiki/envelope, https://en.wiktionary.org/wiki/envelopes