Where does “diachronical” come from?

diachronical (English) comes from English diachronic, from English chronic, from English chronical, from Old French cronike, from Latin chronicus, from Ancient Greek χρονικός, from Ancient Greek -ικός, from Ancient Greek -κός — -y, -ic.

Ancestry of “diachronical”, step by step

StepLanguageWordMeaning
1EnglishdiachronicOccurring over or changing with time; Of,...
2EnglishchronicOf a problem, that continues over an extended...
3EnglishchronicalObsolete form of chronic; Misspelling of...
4Old FrenchcronikeAlternative form of cronicle
5LatinchronicusOf or pertaining to time; chronic
6Ancient Greekχρονικόςof or concerning time, temporal; chronological
7Ancient Greek-ικόςof or pertaining to, in the manner of; -ic
8Ancient Greek-κόςforms adjectives with the sense of 'of or...
9Proto-Indo-European-ḱos-y, -ic
Every word from Proto-Indo-European -ḱosEvery word from Ancient Greek -ικόςEvery word from Ancient Greek -κός