The term 'added (on)' can be expressed in a variety of ways. TACKED, with 6 letters, means to attach something firmly. EXTRA, with 5 letters, means an additional amount or thing. ANNEXED, with 7 letters, means to attach something to a larger entity. APPENDED, with 8 letters, means to add something at the end of a document. Hired, with 5 letters, means to employ someone for a job. All of these words refer to the concept of adding something to an existing entity.