symbiont

noun

sym·​bi·​ont ˈsim-bē-ˌänt 

: an organism living in symbiosis

especially : the smaller member of a symbiotic pair

Examples of symbiont in a Sentence

Recent Examples on the Web

For instance, the bacterium Carsonella ruddii, which lives as a symbiont within the guts of sap-feeding insects, has an even smaller genome than Sukunaarchaeum, at around 159,000 base pairs. —Jake Buehler, Quanta Magazine, 24 Nov. 2025

Scientists hadn’t previously discovered aggressive animal symbionts living together inside a single plant host. —Guillaume Chomicki, The Conversation, 10 July 2025

Lichens are symbionts, or two organisms that are in a cooperative relationship. —Elizabeth Rayne, ArsTechnica, 19 Apr. 2025

One of the more nauseating aspects of the rise of environmental, social, and governance (ESG) investing and its symbiont, stakeholder capitalism, was the spectacle of large financial institutions rallying behind the climatist agenda, which is what that E was all about. —Andrew Stuttaford, National Review, 14 Jan. 2025

Word History

Etymology

borrowed from German Symbiont, probably altered (after Greek ont-, stem of ṓn, present participle of eînai "to be") from symbiount-, stem of symbiôn, present participle of symbioûn "to live together" — more at symbiosis

First Known Use

1887, in the meaning defined above

Kids Definition

symbiont

noun

sym·​bi·​ont ˈsim-ˌbī-ˌänt 

-bē-

: an individual living in symbiosis

especially : the smaller member of a symbiotic pair

Medical Definition

symbiont

noun

sym·​bi·​ont ˈsim-ˌbī-ˌänt  -bē- 

: an organism living in symbiosis

especially : the smaller member of a symbiotic pair

called also symbiote

symbiontic

ˌsim-ˌbī-ˈänt-ik, -bē- 

adjective