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
"Certain temperature conditions may foster all-female populations, which can be overcome through facultative parthenogenesis," he said.
From Salon • Jun. 10, 2023
Note that there is no clear line that differentiates facultative carnivores from omnivores; dogs would be considered facultative carnivores.
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
Moreover, the extent of the "facultative" divergence attainable by prisms shows a considerable latitude.
From Schweigger on Squint A Monograph by Dr. C. Schweigger by Schweigger, C.
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.
