{ En"vel*ope (?; 277), En*vel"op
(?; 277), } n. [F.
enveloppe.]
1. That which envelops, wraps up, encases,
or surrounds; a wrapper; an inclosing cover; esp., the cover or wrapper of a
document, as of a letter.
2.
(Astron.) The nebulous covering of the head or nucleus of
a comet; -- called also coma.
3. (Fort.) A work of earth, in the
form of a single parapet or of a small rampart. It is sometimes raised in the ditch
and sometimes beyond it.
Wilhelm.
4. (Geom.) A curve or surface which is tangent to
each member of a system of curves or surfaces, the form and
position of the members of the system being allowed to vary according to some continuous law. Thus, any curve is the
envelope of its tangents.
Hear it pronounced