The word entered English in the 1600s as a combining form (prefix), borrowed from Late Latin allos, from Greek allos — literally “other.” The root allos (“other”) connects all- to the entire divergence roots: allopathy (all- + pathos → treatment with a different/opposite remedy), allogeneic (all- + genes → originating from another individual of the same species), and allostasis (all- + -stasis→ achieving stability through change/different states). The qualitative prefix all- is productive in immunology, pharmacology, and pathology: e.g., allograft, allotype, and allochromatic.