/ˈenvələʊp;ˈɒn- ||; ˈɛnvəˌlop; ˈɑn-/noun [C] the paper cover for a letter 信封
After writing a letter you address the envelope, seal it and stick a stamp in the top right-hand corner. 写好了信，就在信封上写上地址(address)，把信封封口(seal)，在信封右上角贴上邮票。 ☞Look at stamped/self-addressed envelope. 参看 stamped／self-addressed envelope。