facultative
Americanadjective
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conferring a faculty, privilege, permission, or the power of doing or not doing something.
a facultative enactment.
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left to one's option or choice; optional.
The last questions in the examination were facultative.
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that may or may not take place; that may or may not assume a specified character.
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Biology. having the capacity to live under more than one specific set of environmental conditions, as a plant that can lead either a parasitic or a nonparasitic life or a bacterium that can live with or without air (opposed to obligate).
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of or relating to the faculties.
adjective
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empowering but not compelling the doing of an act
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philosophy that may or may not occur
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insurance denoting a form of reinsurance in which the reinsurer has no obligation to accept a particular risk nor the insurer to reinsure, terms and conditions being negotiated for each reinsurance
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biology able to exist under more than one set of environmental conditions Compare obligate
a facultative parasite can exist as a parasite or a saprotroph
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of or relating to a faculty
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Capable of existing under varying environmental conditions or by assuming various behaviors. Bacteria that are facultative aerobes can live in both aerobic and anaerobic environments. A facultative parasite can live independently of its usual host.
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Compare obligate
Other Word Forms
Etymology
Origin of facultative
First recorded in 1820-25; from French facultative (feminine) “conveying or granting a right or power,” from faculté “knowledge, learning, physical or moral capacity,” ultimately from Latin facultāt-, the stem of facultās (originally a doublet of the noun facilitās “ease, ease of performance or completion, facility”) “ability, power, capacity” + -ative adjective suffix; see faculty ( def. ), -ive ( def. )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"Fascinatingly, we found that the obligately agamospermous Balanophora species were all island species -- and we speculate that more Balanophora species may be facultative, or even obligate, agamosperms."
From Science Daily ● Dec. 20, 2025
However, there remain many unknowns about parthenogenesis, particularly the form known as facultative parthenogenesis, which is quite rare and only happens in animals that sexually reproduce.
From Salon ● Jul. 28, 2023
Sketch a graph that predicts the distribution of aerobic, facultative anaerobic and obligatory anaerobic bacteria along the length of the entire intestine based on these parameters.
From Textbooks ● Jun. 9, 2022
On the issue of facultative reinsurance, whereby it insures bundles of risk in a job lot, Swiss Re said it expected to finalise a policy for the oil and gas sector in 2023.
From Reuters ● Mar. 17, 2022
While some species grow strictly under one condition or the other, and hence are obligate aerobes or anaerobes, others possess the ability of growing under either condition and are known as facultative or optional forms.
From Outlines of Dairy Bacteriology, 8th edition A Concise Manual for the Use of Students in Dairying by Russell, H. L. (Harry Luman)
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
