(finance) to undertake to purchase at an agreed price any unsold portion of (a public issue of shares, etc)
2.
to accept financial responsibility for (a commercial project or enterprise)
3.
(insurance)
to sign and issue (an insurance policy) thus accepting liability if specified losses occur
to insure (a property or risk)
to accept liability up to (a specified amount) in an insurance policy
4.
to write (words, a signature, etc) beneath (other written matter); subscribe
5.
to support or concur with (a decision, statement, etc) by or as if by signature
Word Origin and History for underwrite
v.
early 15c., from under + write (v.). A loan-translation of Latin subscribere (see subscribe). Used literally at first; modern sense of "to accept the risk of insurance" (1620s) is from notion of signing a marine insurance policy. Meaning "to support by a guarantee of money" is recorded from 1890.