If one thing is added on to another, it is attached to the other thing, or is made a part of it. Holidaymakers can also add on a week in Majorca before or after the cruise To the rear is a large dining room -- added on early this century
If you add on an extra amount or item to a list or total, you include it. Many loan application forms automatically add on insurance
Term used to describe purchasing a second cellular phone on the same contract, each having its own airtime package and billing
{i} addition, supplement, something added on; (Computers) component added to a computer in order to improve performance; accessory, thing added as an extra to another; extra charge, additional charge
add to the very end; "He appended a glossary to his novel where he used an invented language"
Add component installed in or connected to a computer that expands the capabilities of the entire system This is also applies to multimedia applications that are installed to expand the capabilities of the web browsers