Where does “subspecialisation” come from?

subspecialisation (English) comes from English specialisation, from English -ation, from Middle English -acioun, from Old French -ation, from Latin -ātiō, from Latin -tiō, from Latin dissertātiō, from Latin dissertus — small stone, pebble; gravel, rubble.

Ancestry of “subspecialisation”, step by step

subspecialisation traces back through two separate lines of ancestry.

via English specialisation

StepLanguageWordMeaning
1EnglishspecialisationNon-Oxford British English standard spelling of...
2English-ationAn action or process; The result of an action or...
3Middle English-aciounForms nouns denoting an action, act, or doing,...
4Old French-ationation
5Latin-ātiō
6Latin-tiōtion, -ation, -ing
7Latindissertātiō(spoken) dissertation, discourse, disquisition
8Latindissertusarranged, disposed; explained
9Latindissereresecond-person singular future passive indicative...
10Latindis-asunder, apart, in two; reversal, removal;...
11Latincalceusshoe
12Latincalxlimestone; chalk; the finish line
13Ancient Greekχάλιξsmall stone, pebble; gravel, rubble

via English sub

StepLanguageWordMeaning
1EnglishsubA submarine; A submarine sandwich: a sandwich...
2EnglishsubstituteTo use in place of something else, with the same...
3Middle Englishsubstituten
4Latinsubstitutussubstituted
5LatinsubstituoI place next to, under, or instead of; I...
6LatinstatuoI set up, station; I establish, determine, fix; I...
7Latinstātusfixed, set, having been set
8Latinstōto stand
9Proto-Italicstaēōstand
10Proto-Indo-Europeansth₂éh₁yetito stand
11Proto-Indo-European*steh₂-
Every word from Ancient Greek χάλιξ