Abstract: The paper aims to investigate the Italian noun “soglia” (threshold). The history and evolution and the conceptual meaning of the term is examined through time, with examples linked to the term itself and to other words – as limit and boundary – with Latin and Tonic Greek etymology, related to the noun itself. Some affine locutions are also discussed. The salient ambiguous aspects of the etymological roots and of the constructs are identified. The noun Soglia, as a concept, adapts its meaning, according to any thematic contexts in which it is used. It does not allow itself to be framed or exhausted by philosophical, historical, literary, astronomical, scientific or mathematical topic. It may refer to multiple subjects but cannot be considered in any univocal meaning, neither simply as a boundary that closes, nor as a threshold, that opens. Some contents, derived from contemporary physics, leads the author to propose a semantic affinity between psychological and physical meaning of soglia, and mentalizes the noun itself, also referring to G. Leopardi’s thought.