Allonge Law & Legal Definition

An allonge is generally an attachment to a legal document that can be used to insert language or signatures when the original document does not have sufficient space for the inserted material. It may be, for example, a piece of paper attached to a negotiable instrument or promissory note, on which endorsements can be written because there isn't enough room on the instrument itself. The allonge must be firmly attached so as to become a part of the instrument.