Where does “oligosyndactylism” come from?

oligosyndactylism (English) comes from English oligo, from English oligonucleotide, from English nucleotide, from English nucleo-, from Latin nū̆cleus, from Latin nuculea, from Latin -eus, from Ancient Greek -εῖος — Creates adjectives from verb stems.

Ancestry of “oligosyndactylism”, step by step

oligosyndactylism traces back through two separate lines of ancestry.

via English oligo

StepLanguageWordMeaning
1EnglisholigoAn oligonucleotide
2EnglisholigonucleotideA short sequence of nucleotides (RNA or DNA), typically with twenty or fewer base pairs
3EnglishnucleotideThe monomer constituting DNA or RNA biopolymer...
4Englishnucleo-Forming words pertaining to nuclei
5Latinnū̆cleus(small) nut
6Latinnuculeapertaining to a small nut
7Latin-eusargentum + API → argenteus; ferrum + API →...
8Ancient Greek-εῖοςForms adjectives, usually with a meaning of "of"...
9Proto-Indo-European-iHwós
10Proto-Indo-European-wósCreates adjectives from verb stems

via English syndactylism

StepLanguageWordMeaning
1Englishsyndactylismsyndactyly
2EnglishsynThat has a torsion angle between 0° and 90°
3EnglishsynonymA word whose meaning is the same as that of...
4Middle Englishsinonyme
5Latinsynōnymumsynonym
6Ancient GreekσυνώνυμοςHaving the same name; Having only one meaning:...
7Ancient Greekσῠν-together; with, together
8Ancient Greekσύνbeside, with
9Proto-Hellenic*ksúnbeside, with
Every word from Proto-Indo-European -wósEvery word from Latin -eusEvery word from English nucleo-