bolt-on 
adjective
1(Of an extra part of a machine) able to be fastened on with a bolt or catch: a bolt-on accessory available for most 35 mm SLRs...
- I estimate the car to be a 1956 model and an American export car complete with bolt-on wheels.
- Well it seems like the boy racers spend a huge fistful of money on cool neon lights, mag wheels and bolt-on performance products - but do they get down and dirty?
- More rumor on the dusty street pointed to a new integrated disc brake mount (no more heavy bolt-on unit).
1.1Denoting a feature, service, etc. that has been or can be added to an existing arrangement: there’s no obligation to buy any type of bolt-on insurance product with a personal loan...
- The last six years have shown conclusively that the strategy of remaining independent and supplementing organic growth with smaller bolt-on acquisitions has failed.
- Such bolt-on deals are aimed at filling holes in a company's core businesses.
- The software is provided to fulfil a specific independent trading function for financial market firms or as a bolt-on component to third-party software.
noun
1A bolt-on part of a machine: the bike’s bolt-ons were worth more than the asking price...
- Built off a 1967 Pontiac GTO Convertible, it featured genuinely interesting bodywork and some wild engine bolt-ons.
- Included with the sale is the car's original owner's manual and some detailed component manuals for the aftermarket bolt-ons.
- In case prestigious BMW bloodlines simply aren't enough to impress, this Bavarian drop-top also features a long list of bolt-ons which transform it from a superb curve carver into a first rate speed machine.
1.1A bolt-on feature, service, etc. some network operators offer bolt-ons to help cut the cost of data usage abroad...
- If you want new features, generally you have to wait for them to implement them (okay, there are some plug-ins and bolt-ons).
- People are finding lots of ways of making this an integral part of the curriculum, not seeing it as a bolt-on.
- At the client level XP is Win2k with bolt-ons, many of them naggy pop-ups.