sensitised

Sensitised is the British English spelling of sensitized, meaning made sensitive or more responsive. In science and everyday use, something that is sensitised has been prepared or exposed to become more reactive to a stimulus, energy, or agent.

In psychology and neuroscience, sensitisation describes an increased reaction to a repeated stimulus. Unlike habituation, which lowers response with exposure, sensitisation heightens responsiveness and can involve neural changes that amplify signaling. It can occur with sensory inputs, drugs, or stressors.

In immunology and medicine, sensitisation to an allergen refers to the state in which the immune system has produced specific antibodies, typically IgE, so that subsequent exposure triggers an allergic reaction. The process may occur during early exposures and manifest as symptoms upon later contact, ingestion, or inhalation.

In photography and materials science, films and emulsions are described as sensitised when they have been treated or coated to respond to light or radiation. Historically, sensitised emulsions were used to capture images, and modern sensors or materials may be chemically or physically sensitised to targeted wavelengths.

In toxicology and occupational health, some substances act as chemical sensitizers because they can provoke hypersensitivity reactions in certain individuals, often after prior exposure. Sensitised individuals may react to very low doses of a chemical.

The term spans disciplines with the common theme of increased reactivity, and its precise meaning depends on context.