write in transitive verb Etymology: Middle English writen in 1. a.: to insert in a document, text, or other writing < write in an amendment to a law > b. (1): to insert (a name not listed on a ballot or voting machine) in an appropriate space by writing or use of a printed sticker (2): to cast (a vote) in this manner 2.: to write to a center of activity or source of supply < teachers are encouraged to write in their requests — James Britton >