Avalize

The act of having a third party (usually a bank or lending institution) guarantee the obligations of a buyer to a seller per the terms of a contract such as a promissory note or purchase agreement. The bank, by "avalizing" the document (usually "by aval" will be written on the document itself), acts as a cosigner with the buyer in the transaction.

Investopedia Says:
To avalize means "to give one's accord". It is a rarely used but is an effective method of securing the rights of the receiving party in the transaction. This is an obligation that a bank will only take on with lucrative customers. It is seen as an act of good faith by both parties.