Definition of underwritten:
(v) :
(transitive) Specifically, to assume financial responsibility for something, and guarantee it against failure.
(v) :
(intransitive, insurance) To act as an underwriter.
(v) :
(transitive) To agree to pay by signing one's name; subscribe.
(v) :
(transitive) To support, lend support to, guarantee the basis of.
(v) :
(transitive) To write below or under; subscribe.
(v) :
(transitive) To sign; to put one's name to.