window envelope meaning in English

(使信纸上收信人姓名住址露出的)开窗信封。

Window envelopes - sizes and position of the window
开窗信封.开窗尺寸和位置
Fig2 . open - window envelopes , showing receivers ' names & addresses , may inaugurate repeated printout
图二：使用开窗式信封来显示收信人的地址和姓名是重复打印的悲剧的开始。
Window envelopes : a style of envelopes in which a clear panel has left in the front so as to show the name and address typed on the letter to be posted
窗口信封:信封的一种款式.信封前面开一个空框,露出待寄信上的姓名和地址。