Where does “antidiphtheric” come from?

antidiphtheric (English) comes from English diphtheric, from English diphtheria, from French diphtérie, from French diphtérite, from Ancient Greek διφθέρα, from Proto-Hellenic dipʰtʰérā.

Ancestry of “antidiphtheric”, step by step

antidiphtheric traces back through two separate lines of ancestry.

via English diphtheric

StepLanguageWordMeaning
1EnglishdiphthericRelating to, or having, diphtheria
2EnglishdiphtheriaA serious infectious disease which causes...
3Frenchdiphtériediphtheria
4Frenchdiphtérite
5Ancient Greekδιφθέραprepared hide, piece of leather; especially as...
6Proto-Hellenicdipʰtʰérā

via English anti

StepLanguageWordMeaning
1EnglishantiOpposed to something; That has a torsion angle...
2Englishanti-Against, hostile to; Contrasting with the norm;...
3Ancient Greekἀντι-anti-, against; like, reminiscent of
4Ancient Greekᾰ̓ντῐ́opposite
Every word from Proto-Hellenic dipʰtʰérāEvery word from Ancient Greek διφθέραEvery word from French diphtérite