The present article is framed within the biosemiotic glossary project as a way to address common terminology within biosemiotic research. The glossary integrates the view of the members of the biosemiotic community through a standard survey and a literature review. The concept of ‘semiotic threshold’ was first introduced by Umberto Eco, defining it as a boundary between semiotic and non-semiotic areas. We review here the concept of ‘semiotic threshold’, first describing its denotation within semiotics via an examination on the history (...) of the concept, its synonyms, antonyms, etymology, usage in other languages and context in which it is used. Then we present a general overview of the survey among researchers, analyzing the difference in responses for the concept of ‘lower semiotic threshold’ and related concepts. From the answers we also review the difference between the general usage of ‘semiotic threshold’ versus its specific use within biosemiotics, and attempt to make a general synthesis of the concept taking into account what we have learned from the survey and the literature review. (shrink)