The story
- Proto-Indo-European*kʷ-
- Proto-Indo-European*kʷos?
- Proto-Indo-European*kʷoider.?
- Proto-Italic*kʷāntos
- Latinquantus
- Proto-Indo-European*dʰeh₁-
- Proto-Italic*θakos
- Medieval Latinquantificō
- English todayquantify
From Medieval Latin quantifico (introduced by Sir William Hamilton in logic).
Etymology from Wiktionary, CC BY-SA 4.0.