means A substance, usually an alcohol-based gel or liquid, that kills or reduces germs on the skin or surfaces without needing soap and water.

from From 'sanitize' plus the agent suffix '-er.' 'Sanitize' comes from 'sanitary,' which traces back to Latin 'sanitas' meaning 'health,' from 'sanus,' 'healthy' — the same root that gives us 'sane' and 'sanatorium.' So a sanitizer is, quite literally, a thing that makes healthy. The word itself is fairly modern, an early-20th-century formation, but it stayed clinical and unglamorous for decades before pandemics gave it star billing.