IPA: /ˈæntiˌmɪsaɪl/
KK: /ˈæntiˌmɪsəl/
Relating to systems or weapons that are intended to intercept and destroy missiles while they are in flight.
The country invested heavily in antimissile technology to protect its borders.
Antimissile is formed from "anti-" (meaning against) and "missile" (from Latin "missilis", meaning capable of being thrown). The word refers to a system or device designed to counter or defend against missiles.
Think of 'anti-' meaning against, and 'missile' meaning something that is thrown. This helps you remember that an antimissile is something that works against thrown projectiles.