symbiosis

noun

sym·​bi·​o·​sis ˌsim-bē-ˈō-səs  -ˌbī- 

plural symbioses ˌsim-bē-ˈō-ˌsēz  -ˌbī- 

1

: the living together in more or less intimate association or close union of two dissimilar organisms (as in parasitism or commensalism)

especially : mutualism

2

: a cooperative relationship (as between two persons or groups)

The symbiosis … between the resident population and the immigrants …

—John Geipel

Did you know?

Symbiosis was adopted by the scientific community in the late 1800s, coming ultimately (via German) from the Greek symbíōsis, meaning “living together, companionship.” Of course, there are a lot of ways to live together and, accordingly, several flavors of symbiosis. When a biological symbiosis between two organisms is mutually beneficial, it is termed mutualism. For example, oxpeckers are birds so named because they “peck” ticks off of infested cattle and wild mammals, a likely satisfying arrangement for both parties, and textbook mutualism. When one organism lives off another at the other’s expense, however (as, for one icky instance, head lice do), it’s called parasitism. If only parents of elementary school students could call upon an equivalent of oxpeckers to engage in mutualistic symbiosis when the need arose, but alas.

Examples of symbiosis in a Sentence

The bird lives in symbiosis with the hippopotamus.

Their professional association was one of symbiosis.

Recent Examples on the Web

The scale of the commercial-military symbiosis between Washington and Silicon Valley is almost incomprehensible. — Alex Capri, Fortune, 4 Aug. 2026

The village is recognized for its symbiosis with the natural environment and development around the tomb of a Sufi master and saint. — Evie Carrick, Travel + Leisure, 28 July 2026

In El Rosario, the trinkets and souvenirs, the tour-bus parking lots, and even the stable of horses for rent all speak to a symbiosis that has only recently come to be. — Vann R. Newkirk Ii, The Atlantic, 28 July 2026

This craft is deeply rooted in our cultural tradition, and the powerful symbiosis between our incredible local creators and a robust industry truly sets us apart in the global marketplace. — Leo Barraclough, Variety, 16 July 2026

Word History

Etymology

borrowed from German Symbiose, borrowed from Greek symbíōsis "living together, companionship," from symbiō-, variant stem of symbioûn "to live with, live together" (from sym- sym- + bioûn "to live, pass one's life," derivative of bíos "life") + -sis -sis — more at quick entry 1

Note: As a term in life sciences German Symbiose was promulgated, if not introduced, by the mycologist Heinrich Anton de Bary (1831-88) in Die Erscheinung der Symbiose: Vortrag gehalten auf der Versammlung der Deutscher Naturforscher und Aertze zu Cassel (Strassburg, 1879); a portion of the lecture appeared earlier as "Ueber Symbiose" in Der Naturforscher, 11. Jahrgang, No. 43, October 26, 1878, pp. 400-04. He defines the word briefly as "the living together of differently denominated organisms" ("[das] Zusammenleben ungleichnamiger Organismen," p. 5). De Bary was probably aware of the slightly earlier synonymous term Symbiotismus, introduced by the plant pathologist Albert Bernhard Frank (1839-1900) in "Ueber die biologischen Verhältnisse des Thallen einiger Krustenflechten," Beiträge zur Biologie der Pflanzen, Band 2 (1877), p. 195.

First Known Use

1877, in the meaning defined at sense 1

Rhymes for symbiosis

• cirrhosis
• fibrosis
• gliosis
• hypnosis
• ichthyosis
• ketosis
• kurtosis
• lordosis
• meiosis
• miosis
• mitosis
• mycosis

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Kids Definition

symbiosis

noun

sym·​bi·​o·​sis ˌsim-ˌbī-ˈō-səs 

-bē-

plural symbioses -ˈō-ˌsēz 

1

: the living together in close association of two different kinds of organisms (as a fungus and an alga making up a lichen) especially when such an association is of benefit to both

2

: a cooperative relationship (as between two persons or groups)

symbiotic

-ˈät-ik 

adjective

symbiotically

-i-k(ə-)lē 

adverb

Medical Definition

symbiosis

noun

sym·​bi·​o·​sis ˌsim-ˌbī-ˈō-səs  -bē- 

plural symbioses -ˌsēz 

1

: the living together of two dissimilar organisms in more or less intimate association or close union

2

: the intimate living together of two dissimilar organisms in a mutually beneficial relationship

especially : mutualism