bookkeeper (n.)

also book-keeper, "person who keeps accounts, one whose occupation is to make a formal balanced record of pecuniary transactions in account-books," 1550s, from book (n.) + keeper. A rare English word with three consecutive double letters. Related: Bookkeeping, which is from 1680s in the sense "the work of keeping account books;" book-keep (v.) is a back-formation from 1886.