Specificita

Specificita (often written specificity in English) is a term used across disciplines to denote either the precision with which a target is characterized, or the capacity of a process to respond to a particular stimulus while ignoring others. In biology and biochemistry, specificity refers to selective interactions, such as enzymes that catalyze a single substrate, antibodies that bind a specific antigen, or receptors that respond to a particular ligand.

In ecology and medicine, specificity has specialized meanings. In diagnostics, test specificity is the proportion of true negatives among all non-diseased individuals, i.e., TN/(TN+FP). High specificity reduces false positives and is contrasted with sensitivity, which measures true positives. The balance between them depends on context and disease prevalence.

In linguistics and semantics, specificity concerns how a noun phrase refers to an identifiable, particular entity versus a non-specific member of a class. In philosophy and information theory, specificity can describe how narrowly a description confines the set of possible referents or outcomes.

Across domains, higher specificity implies greater discrimination or precision, but may reduce coverage or flexibility. The term can therefore denote both a qualitative property (how selective) and a quantitative measure (rates of correct identifications). See also sensitivity, positive predictive value, and reproducibility.