See add something ↔ on for more
add-on
ˈadd-on
noun [countable]
1. something extra that is added to an existing plan, agreement, law etc
add-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 board
3. a product that is designed to be used with another product
ˈadd-on
noun [countable]1. something extra that is added to an existing plan, agreement, law etc
add-on to
2. a piece of equipment that you connect to a computer to improve its performance:
3. a product that is designed to be used with another product