Type of antimicrobial that kills (or irreversibly inactivates) all bacteria, fungi, and viruses (called microbials, microbiologicals, microorganisms), including their spores (hardened form) which are among the most difficult-to-kill forms of life. Some sterilants (such as pure chlorine or chlorine dioxide) are powerful oxidizing agents. Non-chemical sterilants include very high temperature and intense radiation. Also called sporicide or sterilizer.