The set of performance limits (such as speed, altitude, and load factor) within which an aircraft, spacecraft, or other system can operate safely; operating envelope.

The engineers expanded the helicopter's flight envelope through rigorous testing.

Mathematics/Physics: a curve or surface that is tangent to each member of a family of curves or surfaces, often used to bound or describe their extremes.

The red line is the envelope of the family of straight lines plotted on the graph.

Biology: a membrane-like outer layer or covering that encloses a cell, spore, or virus particle.

The viral envelope helps the pathogen evade the host’s immune response.

envelopeприлагательное

Attributive: relating to or designed for use with envelopes.

The office purchased an envelope printer for bulk mailing.

Audio engineering (attributive): relating to the attack, decay, sustain, and release characteristics of a sound signal.

The synthesizer includes an envelope generator for shaping each note.