- Round
- A self-navigated, self-timed circuit of named summits in a British mountain range, completed within a fixed time limit — usually 24 hours — with no marked course, no aid stations and no entry fee.
- Fastest Known Time (FKT)
- The record-keeping convention used for routes with no official race, no fixed date and no timing chip. fastestknowntime.com is the community database this site cites for current Round records.
- Munro
- A Scottish mountain over 3,000 ft (914.4m). There are 282 recognised Munros; the Ramsay Round crosses 23 of them, plus Ben Nevis.
- UTMB World Series
- The global circuit of branded ultra-trail races that includes UTMB itself in Chamonix. Announced in 2021 and launched in 2022, replacing the earlier Ultra-Trail World Tour. Eryri by UTMB and Arc of Attrition by UTMB are its two UK races.
- Running Stones
- The UTMB World Series' qualification currency: finishing a World Series race earns Running Stones, used to enter the lottery for a place at the UTMB World Series Finals in Chamonix.
- Hydrostatic head (Schmerber)
- A measure of how waterproof a fabric is, in millimetres of water column. UTMB World Series 100-mile races require a minimum of 20,000mm for the mandatory waterproof jacket.
- Supported / unsupported
- Categories used in Round records: 'supported' means a runner has pacers, navigation help or resupply from others along the way; 'unsupported' means they carry and navigate entirely alone.
- Verifying club
- An independent body that confirms a Round completion, typically requiring a witness at every summit with a recorded time. Only the Bob Graham Round has one — the Bob Graham 24 Hour Club, proposed in 1971.
- Cut-off
- The maximum time allowed to reach a given point on an organised race course. Miss it, and the usual result is withdrawal, regardless of physical condition — a feature Rounds don't have.
- DNF (Did Not Finish)
- Standard shorthand for withdrawing from a race or Round attempt before completion, for any reason — injury, cut-off, weather or a judgment call to stop.
- Aid station / checkpoint
- A staffed point on an organised race course offering food, water, or medical support. Rounds have none — any support a runner gets is arranged privately, not provided by an organiser.
- Elevation gain
- The cumulative climbing over a route, usually given in metres or feet. It's tracked separately from distance because two routes of the same length can demand very different effort.
- Fell running
- Off-road running over upland terrain, particularly associated with northern England and Scotland — the broader sport that Rounds, and races like the Spine Race and Arc of Attrition, belong to.
- Time limit vs. time target
- A time limit is enforced by an organiser — miss it and the result doesn't count, as on the Spine Race. A time target, like the Paddy Buckley and Ramsay Rounds' 24 hours, is a convention the community tracks, not a rule any club enforces.
- Mandatory kit
- The list of equipment an organiser requires runners to carry, checked at registration or on the course. Rounds have no official mandatory kit; organised races and winter races do, and the lists differ by event.