1. Linux
2. TempleOS
3. Mac
4. Intel Management Engine
5. W.*

EDIT: I'll add any system that gets at least five votes in the comments. Let's roll.

1. An offensive word meaning unpleasant, silly, incompetent, annoying, senile, elderly or childish person.
2. Surprisingly, it is also a personal pronoun in Old English 😁 (though spelled ġit)

This one's easy. Lineage is ancestry, just like Lineage OS comes from CyanogenMod.