coccidioidin
noun
coc·cid·i·oi·din
| \ -ˈȯid-ᵊn, -ˈȯi-ˌdin
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Medical Definition of coccidioidin
: an antigen derived from a fungus of the genus Coccidioides (C. immitis) while in its mycelial phase and used to detect skin sensitivity to and, by inference, infection with this organism — compare spherulin