Limen

Limen is a noun derived from the Latin word for threshold. In scholarly usage, it denotes a boundary or point of transition between two states, categories, or conditions. The term is applied across disciplines to indicate a limit rather than a specific physical structure, signaling where one state ends and another begins.

In psychology and psychophysics, limen describes perceptual thresholds. The absolute limen is the minimum stimulus intensity needed for conscious detection, typically measured to determine when a stimulus becomes perceptible. The difference limen, also called the just noticeable difference, is the smallest detectable change in a stimulus. These concepts underpin methods for studying sensation, perception, and sensory acuity.

In anatomy and biology, limen appears in descriptive usage to denote borders between regions or components within an organ or tissue. It signals a transition rather than naming a fixed anatomical feature, and is more common in formal or historical terminology than in everyday anatomical language.

In philosophy, theology, and cultural studies, limen is associated with liminality—the threshold state between two modes of being, spaces, or identities. This usage emphasizes transition, ambiguity, and potential that come with crossing boundaries, whether in social rites, spatial contexts, or subjective experience.