A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life. Disinfectants are generally distinguished from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides—the latter are intended to destroy all forms of life, not just microorganisms. Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. It is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface.

रोगाणुओ और सूक्ष्माणुओं को मार डालने के लिए निस्संक्रामकों (Disinfectants) का प्रयोग होता है। इससे संक्रामक रोगों को रोकने में सहायता मिलती है। इन्हें 'विसंक्रामक', 'विसंक्रामी' या 'संक्रमणहारी' भी कहते हैं।