The story
- Proto-Indo-European*né
- Proto-Indo-European*n̥-
- Proto-Germanic*un-
- Proto-West Germanic*un-
- Old Englishun-
- Middle Englishun-
- Englishun-
- Proto-Indo-European*né
- Proto-Germanic*ne
- Proto-Indo-European*ís?
- Proto-Indo-European*h₁óynos
- Proto-Germanic*ainaz
- Proto-Germanic*nainaz
- Proto-West Germanic*nain
- Old Englishnān
- Middle Englishnon
- Old Englishnān
- Old Englishnān-
- Middle Englishnon-
- Englishnon-
- Proto-Indo-European*sent-
- Proto-Italic*sentiō
- Latinsentiō
- Latinsēnsu
- Proto-Germanic*sinnaz
- Frankish*sinn
- Vulgar Latin*sennus
- Old Frenchsens
- Middle Englishsense
- Englishsense
- Englishnonsense
- Proto-Indo-European*h₂el-
- Proto-Indo-European*h₂élisder.?
- Englishnonsensical
- English todayunnonsensical
From un- + nonsensical.
Etymology from Wiktionary, CC BY-SA 4.0.