- envelope
- envelope [än′və lōp΄, en′′və lōp΄]n.[Fr & OFr enveloppe < OFr envoluper: see ENVELOP]1. a thing that envelops; wrapper; covering2. a folded paper container as for a letter, usually with a gummed flap for sealing3.a) the outer covering of a rigid airshipb) the bag that contains the gas in a balloon or nonrigid airship4. the set of limitations, as for a particular aircraft, system, etc., within the boundaries of which it can operate safely and efficiently5. a set of limits or boundaries: usually in the informal phrase push the envelope, to go beyond or attempt to go beyond established rules, limits, expectations, etc.6. Astron. a cloudy mass surrounding the nucleus of a comet; coma7. Biol. any enclosing membrane, skin, shell, etc.8. Math. a curve that is tangent to every one of a family of curves, or a surface that is tangent to every one of a family of surfaces
English World dictionary. V. Neufeldt. 2014.