A circular note is a document request by a bank

Bank

A bank is a financial institution that serves as a financial intermediary. The term "bank" may refer to one of several related types of entities:...

to its
foreign correspondents to pay a specified sum of money to a
named person. The person in whose favour a circular note is
issued is furnished with a letter (containing the signature of an
official of the bank and the person named) called a letter of
indication, which is usually referred to in the circular note,
and must be produced on presentation of the note. Circular
notes are generally issued against a payment of cash to the
amount of the notes, but the notes need not necessarily be
cashed, but may be returned to the banker in exchange for the
amount for which they were originally issued. A forged signature
on a circular note conveys no right, and as it is the duty of the
payer to see that payment is made to the proper person, he
cannot recover the amount of a forged note from the banker
who issued the note.