envelope

sobre

Cubierta plana de papel donde se mete una carta o tarjeta, sobre todo para enviarla por correo.

En inglés sencillo: A flat paper cover that holds a letter or card, especially when you send it by post.

• Put the letter in an envelope.
• She wrote my address on the envelope.
• Who sent this empty envelope?

Expresiones frecuentes: sealed envelope, open an envelope, envelope address, paper envelope

envoltura

Capa o cubierta exterior que rodea algo por completo.

En inglés sencillo: A layer or outer cover that surrounds something completely.

• A protective envelope surrounds the cell.
• The balloon’s envelope was filled with hot air.
• The planet has a thin envelope of gas.

Cómo se usa: an envelope of something (An envelope of hot gas surrounds the star.)

Sinónimos: covering, outer layer

Expresiones frecuentes: outer envelope, protective envelope, envelope of gas

envolvente operativa, envolvente de vuelo

Límites dentro de los cuales una máquina o un sistema puede funcionar de manera segura y correcta.

En inglés sencillo: The limits within which a machine or system can work safely and properly.

• The aircraft stayed within its flight envelope.
• Engineers tested the motor’s operating envelope.
• Flying outside the envelope can damage the aircraft.

Cómo se usa: within/outside the envelope (The pilot kept the aircraft within its flight envelope.)

Sinónimos: operating limits

Expresiones frecuentes: flight envelope, operating envelope, performance envelope