jiffy bag

/JH IH1 F IY0 B AE0 G/
noun
  1. 1

    A large thick envelope, now usually coated with foam or bubblewrap, used to protect fragile items in the mail.

Source: https://en.wiktionary.org/wiki/Jiffy%20bag, https://en.wiktionary.org/wiki/jiffy%20bag, https://en.wiktionary.org/wiki/padded%20envelope