Where does “null suffix” come from?

null suffix (English) comes from English suffix, from Latin suffixus, from Latin suffigo, from Latin sub, from Proto-Italic supo, from Proto-Indo-European upó, from Proto-Indo-European h₃ewp-.

Ancestry of “null suffix”, step by step

null suffix traces back through two separate lines of ancestry.

via English suffix

StepLanguageWordMeaning
1EnglishsuffixA morpheme added at the end of a word to modify...
2Latinsuffixusfastened
3LatinsuffigoI fasten or fix onto
4Latinsubunder, beneath; behind; at the feet of
5Proto-Italicsupounder
6Proto-Indo-Europeanupóunder, below
7Proto-Indo-Europeanh₃ewp-

via English null

StepLanguageWordMeaning
1EnglishnullA non-existent or empty value or set of values;...
2Middle Frenchnulnobody; no one; none
3Old Frenchnulnobody; no one; none
4Latinnūllusno one, none, not any, nothing
5Proto-Italicoinoscardinal number 1 Previous: n/a Next: *duō;...
6Proto-Indo-Europeanóynosone; single
Every word from Proto-Indo-European h₃ewp-Every word from Proto-Indo-European upóEvery word from Proto-Italic supo