| Noun | 1. | mortgage-backed security - a security created when a group of mortgages are gathered together and bonds are sold to other institutions or the public; investors receive a portion of the interest payments on the mortgages as well as the principal payments; usually guaranteed by the government certificate, security - a formal declaration that documents a fact of relevance to finance and investment; the holder has a right to receive interest or dividends; "he held several valuable securities" |