The name, sometimes translated as "cooking place of the deer" or interpreted as relating to wild or roaming people, refers to a type of ancient outdoor cooking site found in extraordinary numbers across Ireland. Thousands have been recorded, making them among the most common field monuments on the island, yet they remain quietly mysterious in terms of exactly who used them, and when, and why in such abundance.

The typical fulacht fia consists of a mound of shattered, fire-cracked stone accumulated over repeated use. The method is well understood: stones were heated in a fire and then dropped into a water-filled trough, bringing it rapidly to the boil. The cracked and spent stones were discarded into a surrounding mound, which is often horseshoe-shaped and frequently found near a stream or boggy ground where a trough could be easily maintained. Most Irish examples date to the Bronze Age, roughly 2000 to 500 BC, though some sites show evidence of use across much longer periods. At Kilpatrick, the site survives not as an upstanding mound but as a spread of that characteristic burnt and fragmented stone, brought to the surface by ploughing and visible as a discolouration and scatter across the field.