To cover the back of; to load or burden.

To write upon the back or outside of a paper or letter, as a direction, heading, memorandum, or address.

To write one's name, alone or with other words, upon the back of (a paper), for the purpose of transferring it, or to secure the payment of a note, draft, or the like; to guarantee the payment, fulfillment, performance, or validity of, or to certify something upon the back of (a check, draft, writ, warrant of arrest, etc.).

To give one's name or support to; to sanction; to aid by approval; to approve; as, to indorse an opinion.

be behind; approve of; "He plumped for the Labor Party"; "I backed Kennedy in 1960"

give support or one's approval to; "I'll second that motion"; "I can't back this plan"; "endorse a new project"

guarantee as meeting a certain standard; "certified grade AAA meat"

in the Housing Court, to write the oral answer of a respondent upon the court copy of the petition infant's compromise: a civil proceeding or motion for obtaining court approval of the settlement of an infant's claim