- to undertake to purchase at an agreed price any unsold portion of (a public issue of shares, etc)
- to accept financial responsibility for (a commercial project or enterprise)
- 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
- to write (words, a signature, etc) beneath (other written matter); subscribe
WordReference Random House Learner's Dictionary of American English © 2015
- to give or contribute a sum of money to guarantee the success of (an undertaking):to underwrite the building of a new library.
- to write one's name at the end of (a policy), thereby becoming responsible in case of certain losses.
- to insure, as for a certain sum.