The story
- Proto-Indo-European*h₂ent-
- Proto-Indo-European*h₂énts
- Proto-Germanic*anda-
- Proto-West Germanic*anda-
- Old Englishand-
- Old Englishon-
- Middle Englishon-
- Englishun-
- Proto-Indo-European*(s)peys-der.?
- Latinspīrō
- Latinspīritus
- Proto-Indo-European*h₂el-
- Proto-Indo-European*h₂élisder.?
- Late Latinspīrituālis
- Old Frenchspiritue
- Middle Englishspiritual
- Englishspiritual
- Englishspiritualize
- Proto-Indo-European*né
- Proto-Indo-European*n̥-
- Proto-Germanic*un-
- Proto-West Germanic*un-
- Old Englishun-
- Middle Englishun-
- Englishun-
- Englishspiritual
- Englishunspiritual
- English todayunspiritualize
From un- (reversive) + spiritualize, or from unspiritual (“not spiritual”) + -ize.
Etymology from Wiktionary, CC BY-SA 4.0.