endosymbiont
noun
en·do·sym·bi·ont
| \ ˌen-dō-ˈsim-ˌbī-ˌänt
, -bē-
\
, -bē-
\
variants:
also endosymbiote \ -ˌōt
\
\
Medical Definition of endosymbiont
: a symbiotic organism living within the body of its partner