To join or unite, as one thing to another, or as several particulars, so as to increase the number, augment the quantity, enlarge the magnitude, or so as to form into one aggregate
make an addition (to); join or combine or unite with others; increase the quality, quantity, zise or scope of; "We added two students to that dorm room"; "She added a personal note to her letter"; "Add insult to injury"; "Add some extra plates to the dinner table"