Definition of "bolt-on"

Some guitars have the neck glued to the body (Les Pauls), some are bolted on (Fenders), and in some the neck is part of one piece of wood that extends through the body (Jackson). The theory of the neck through the body design is that if the pickups, bridge, and the strings (from tuners to tailpiece) are mounted on the same piece of wood, sustain will be greatly enhanced. In practice, a well joined glue-on and a properly fitted bolt-on will sustain just as well.

1988, Michael Ross, “The Electric Guitar as an Acoustic Instrument”, in Getting Great Guitar Sounds: A Non-technical Approach to Shaping Your Personal Sound, Milwaukee, Wis.: Hal Leonard Books, page 18

I would draw a distinction between transplants and cross-fertilisation. […] Cross-fertilisation implies a different, more indirect process. It implies that an external stimulus promotes an evolution within the receiving legal system. The evolution involves an internal adaptation by the receiving legal system in its own way. The new development is a distinctive but organic product of that system rather than a bolt-on.

1998, John Bell, “Mechanisms for Cross-fertilisation of Administrative Law in Europe”, in Jack Beatson, Takis Tridimas, editors, New Directions in European Public Law, Oxford: Hart Publishing, page 147

Should not a curriculum for the twenty-first century be organised more effectively around the new technology? At present, it remains an addition to most subjects – a bolt-on.

2011, Alan Barrow, “The Changing Educational Scene”, in Christine Bold, editor, Supporting Learning and Teaching, 2nd edition, Abingdon, Oxon., New York, N.Y.: Routledge, page 26

Friday night's crowning victory at The Hawthorns was the 25th in 30 league matches since Antonio Conte's decisive re-gearing of his team in September, the tactical switches that have coaxed such a thrilling run from this team of bolt-ons and upcycled squad players, most notably Victor Moses, who was dredged out of the laundry bin in the autumn to become a key part of the title surge.

2017 May 13, Barney Ronay, “Antonio Conte’s brilliance has turned Chelsea’s pop-up team into champions”, in The Guardian‎, London, archived from the original on 9 September 2017

[I]f an innovation has reached the maturity stage of the product life-cycle, then perhaps its functionality will be developed to provide a ‘bolt-on’, with the core of the innovation remaining essentially the same. A classic example of a sustained innovation is the mobile phone, where functionality is increased by adding on extra capabilities, such as video, Internet acss, GPS tracking systems, music, and email.

2009, Simran K. Grewal, Lisa Harris, “Learning Virtually or Virtually Distracted?: The Impact of Emerging Internet Technologies on Pedagogical Practice”, in Niki Panteli, editor, Virtual Social Networks: Mediated, Massive and Multiplayer Sites, Basingstoke, Hampshire: Palgrave Macmillan, page 18

PureGym (puregym.com), which has more than 200 gyms across Britain, charges from £8.99 to £17.99 a month, with "bolt ons" available.

2018 January 6, Ali Hussain, “New year, new financial you: The detox that could save £1800”, in The Times‎, London

[T]he first model of this now most famous line of related types, the [Gibson] Les Paul also appeared in 1952, […] The trapeze style tailpiece and combined bar bridge was also fitted, although this gave way to a bolt-on bar bridge by 1953.

1979, Ken Achard, “The Fabulous Fifties”, in The History and Development of the American Guitar (Guitar Magazine Project; G 128), London: New Musical Services; republished Westport, Conn.: The Bold Strummer, 1990, page 32

Marketing is not an option, a bolt-on activity, or for moments when 'time allows'; it must be present all the time as the company goes about its business.

1997, Patrick Forsyth, Robin Birn, “Afterword”, in Marketing in Publishing (A Blueprint Book), London, New York, N.Y.: Routledge, page 150

They force organizations away from traditional ‘bolt-on’ safety, seen as being someone else’s problem.

1998, Martin J. Barnard, “The CDM Regulations: Keeping an Air of Realism”, in Martin J. Barnard, editor, Health and Safety for Engineers, London: Thomas Telford Publishing, page 26

This week we take a close look at four top contenders in the multitasking arena […] All the multitasking systems available for microcomputers today fall into one of two distinct categories: "bolt-on" multitaskers, which add multitasking to an operating system (DOS, for example) that originally executed one task at a time; and "built-in" multitaskers, which are part of the operating system by design.

1990 September 24, Brett Glass, Tracey Capen, “Orchestrating Applications: While Desqview Referees MS-DOS Applications, Three Graphics-based Multitaskers Promote Cooperative Look-alike Environments”, in InfoWorld, volume 12, number 39, Menlo Park, Calif.: InfoWorld Publishing, page 63, column 4

Enhanced Data Rates for Global Evolution (EDGE), also known as Enhanced GPRS (EGPRS), is a digital mobile phone technology which acts as a bolt-on enhancement to 2G and 2.5G General Packet Radio Service (GPRS) networks.

2007, “Enhanced Data Rates for GSM Evolution”, in Jielin Dong, editor, Network Dictionary, Saratoga, Calif.: Javvin Technologies, page 177