Where does “superextension” come from?

superextension (English) comes from English Extension, from Middle English extensioun, from Old French estension, from Latin extensio, from Latin -tiō, from Latin dissertātiō, from Latin dissertus, from Latin disserere — small stone, pebble; gravel, rubble.

Definitions

Ancestry of “superextension”, step by step

superextension traces back through two separate lines of ancestry.

via English Extension

StepLanguageWordMeaning
1EnglishExtensionThe act of extending; a stretching out; enlargement in length, breadth, or time; an increase
2Middle Englishextensioun
3Old Frenchestension
4Latinextensioextension, stretching; swelling, tumour
5Latin-tiōtion, -ation, -ing
6Latindissertātiō(spoken) dissertation, discourse, disquisition
7Latindissertusarranged, disposed; explained
8Latindissereresecond-person singular future passive indicative...
9Latindis-asunder, apart, in two; reversal, removal;...
10Latincalceusshoe
11Latincalxlimestone; chalk; the finish line
12Ancient Greekχάλιξsmall stone, pebble; gravel, rubble

via English super

StepLanguageWordMeaning
1EnglishsuperOf excellent quality, superfine; better than...
2Englishsuper-egoAlternative spelling of superego
3GermanÜber-Ichsuperego
4GermanIchego, the Ich; self, me, him, etc
5Middle High GermanichI
6Old High GermanihI
7Proto-West GermanicikI
8Proto-Germanic*ek
9Proto-Indo-Europeanéǵh₂I
Every word from Ancient Greek χάλιξEvery word from Latin -tiōEvery word from Latin dis-