It's common to mistake that only Halides have names ending with -ide
However, there are many other ions that aren't Halides, but still have the suffix
Examples include:
Cyanide - [CN](-)
Sulfide - [S](2-)
Nitride - N(3-)
Oxide - O(2-)
Peroxide - [O2](2-)
Halide - H(-)
In case you haven't noticed, all the -ides I have mentioned have negative charges
So, there's your answer. Negatively charged ions, or anions, usually have names ending in -ide
