envelope
noun [ C ] uk/ˈen.və.ləʊp/ us/ˈɑːn.və.loʊp/
A2 信封
a flat, usually square or rectangular, paper container for a letter
- More examples
- I folded the letter in half and put it in an envelope.
- Send a self-addressed envelope for our free catalogue.
- An envelope was waiting for me when I got home.
- Do you recognize the writing on the envelope?
- The teacher opened the sealed envelope containing the exam papers.
Idiom
on the back of an envelopeidiom 匆忙地;粗略地
in a hurried way, without much detail
The prices were very roughly calculated - it looked as though he'd done them on the back of an envelope. 计算出的价格不很精确——看上去似乎他只是粗略算了一下。