Asphalt reaches Middle English aspalt, Late Latin aspaltus and Greek asphaltos. The modern spelling has h where the two intermediate forms shown here do not.
The selected Latin form is aspaltus, as given in this source. Asphaltum is also a modern English variant; it is not an extra card in this sequence.
Sources
- Merriam-Webster: asphalt
Noun Word History gives the chain; the headword lists asphaltum as a variant and the first-use records distinguish the older noun from the later verb.
- Online Etymology Dictionary · asphalt
Meanings of the older forms on the word path.
- logeion.uchicago.edu · ἄσφαλτος
Meanings of the older forms on the word path.
- logeion.uchicago.edu · asphaltus
Meanings of the older forms on the word path.