endosymbiont

[en-doh-sim-bee-ont, -bahy-]

noun

a symbiont that lives within the body of the host.

Also en·do·sym·bi·ote

[en-doh-sim-bee-oht, -bahy-] /ˌɛn doʊˈsɪm biˌoʊt, -baɪ-/.

Origin of endosymbiont

First recorded in 1935–40; endo- + symbiont

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019