envelope

• 用于装信件或文件以便邮寄的扁平纸质容器，通常为长方形。也指包裹或覆盖某物的外层、外壳或封套。

A flat, usually rectangular paper container used for enclosing a letter or document for mailing.

1. Paper container for lettersA2formal

   A flat, usually rectangular paper container used to enclose a letter or document for mailing.

   信封

   • She sealed the letter in an envelope.
   • Please write the address clearly on the envelope.
   • He tore open the envelope to read the invitation.

   同义词coverwrapper

2. Something that surrounds or enclosesB2formal

   A covering or container that surrounds something.

   外壳

   • The gas envelope around the planet is very thin.
   • The building is protected by a glass envelope.
   • The envelope of air around the Earth is called the atmosphere.

   同义词casingcloakcoatingcontainercoveringhousingsheathshellshroudsurroundveilwrapper

   反义词contentcoreinterior