From Longman Dictionary of Contemporary Englishadd something ↔ on (also add something on something) phrasal verbto include or put on something extra proposals to add a penny on income tax to The private chapel was added on to the church much later. → add→ See Verb table
Examples from the Corpus
add on• He nodded add then moved on.• If you use the real thing, you can use less, Medrich added.• We should also, however, add a comment on a negative aspect, concerning the idea of applicability.• The Senate added restrictions on habeas corpus, or the right of prisoners to appeal against death sentences.• John Bryant, D-Tex., wants to add a near-prohibition on hiring foreign workers.• Over the coming months the looming introduction of euro notes and coins is bound to add to pressures on the currency.• The opportunity has also been taken to add office space on the ground floor by converting the arcade.• It was designed to give a driver added head protection on the left side of the cockpit.add-onˈadd-on noun [countable] 1 something extra that is added to an existing plan, agreement, law etcadd-on to We bought legal protection as an add-on to our home insurance policy.2 a piece of equipment that you connect to a computer to improve its performance an add-on circuit board3 a product that is designed to be used with another productExamples from the Corpus
add-on• Add-ons such as modems and DVD drives can easily cost you hundreds of dollars.• Instructional changes were limited and uneven, and educators largely viewed the program as an add-on.• For users, they are still expensive add-on features and come with their own set of integration problems.• The present pattern of' add-on development will continue.• But in terms of add-on cost the calculation is simple.• The Senate's add-ons to the proposed budget are likely to cause controversy.• But over the years some had gained screened porches and various add-ons.From Longman Business Dictionaryadd-onˈadd-on noun [countable]1MARKETINGa product that is sold to be used with another productYou can have legal insurance as an add-on to a household policy.2COMPUTING a piece of equipment or software that you connect to a computer, usually in order to improve its performanceWe’ve compiled an extensive list of add-ons to make browsing with Internet Explorer more productive. —add-on adjective [only before a noun]add-on software 