To write below or under; subscribe.
To subscribe (a document, policy etc.) with one's name.
To sign; to put one's name to.
To agree to pay by signing one's name; subscribe.
Specifically, to assume financial responsibility for something, and guarantee it against failure.
To act as an underwriter.
To support, lend support to, guarantee the basis of.
To submit to; put up with.
The act of something being underwritten financially.