underwrite
Underwrite (verb) means to write your name underneath something, especially to show your agreement.
Etymology
Came into English via Middle English underwriten, which developed from Old English underwrītan (“to write at the foot of, write under, subscribe”). Compare Dutch onderschrijven (“to endorse”), German unterschreiben (“to sign; endorse”) and Danish underskrive (“to sign; endorse”). By surface analysis, it is under- + write.