The word has clear Finnic cognates, especially Estonian hiis ‘(sacred) grove / sacred place’, and related forms (e.g., Estonian hiid ‘giant’). It also has several Finnish and Finnic derivatives (notably hitto, hiitto, and others), reflecting later semantic developments and taboo-avoidance strategies typical of “power words.” The Finnic term has been borrowed into North Sámi (e.g., hiiˈdâ ‘devil’), indicating later contact and spread of the demonized sense. A prominent hypothesis links Finnic hiisi to a Scandinavian/Germanic word-family meaning something like a lair / resting place / hide, with a plausible semantic bridge via “place of lying/resting” → “grave/burial place” → “cult place.” Koski discusses this as a serious possibility, though it remains a hypothesis rather than a settled fact.
Hiisi has several layered meanings in Finnish and related languages but in its core it refers to a sacred place, grove, forest, a graveyeard in the forest or other sacred place in the old Finnish forest religion. Some of the epic songs and early documentation refers hiisi to be a Forest power that controls animals and the hunt. These meanings are similar across the taiga boreal forest zone of the northern part of Earth. This article traces the evolution and subsequent loss of hiisi in Finland from the 13th century to 2025. The article proposes that this endemic cultural concept is the equivalent of the English concept community-conserved area – ICCA. The article mentions a long self-reflection process in Finland to find appropriate cultural concept of this important, emergent conservation meaning. Hiisi, despite the loss of meaning between 1700-1900s, links both the ancient and the re-emergent meanings associated with community- and village-relevant forests, groves and the biocultural and endemic meanings associated with them.
In Finnish usage today, hiisi most commonly refers to a malevolent supernatural being (roughly “devil/demon/evil spirit”), and it also appears in euphemistic or expletive expressions; older layers of the word include “troll/giant/forest being.” Older (pre-/early Christian) meaning and origin of the concept: Historical and comparative Finnic evidence indicates that the oldest recoverable sense of hiisi was a “cult place” (a sacred site in the landscape), and possibly an even earlier sense connected to a “burial place.” The original “sacred-site” meaning blurred over time, the word persisted in place-names and fixed phrases and then underwent reinterpretation, contributing to later folkloric readings such as “giant/devil” figures associated with older stone mounds and “hiisi sites.”