facultative

[ fak-uhl-tey-tiv ]

adjective

1. conferring a faculty, privilege, permission, or the power of doing or not doing something:

   a facultative enactment.

2. left to one's option or choice; optional:

   The last questions in the examination were facultative.

3. that may or may not take place; that may or may not assume a specified character.
4. 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 ( obligate ).
5. of or relating to the faculties.

facultative

/ ˈfækəltətɪv /

adjective

1. empowering but not compelling the doing of an act
2. philosophy that may or may not occur
3. 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
4. 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

5. of or relating to a faculty

facultative

/ făk′əl-tā′tĭv /

1. 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.
2. Compare obligate

Derived Forms

• ˈfacultatively, adverb

Other Words From

• facul·tative·ly adverb
• non·facul·tative adjective

Word History and Origins

Origin of facultative¹

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

Facultative multicellular organisms are organisms that can exist either as single cells or in a multicellular form depending on environmental conditions.

From Science Daily

The variability of cats’ social tendencies has a fancy name: “facultative sociality.”

From Slate

For the first time, scientists have induced facultative parthenogenesis, a form of asexual reproduction, in an animal that usually reproduces sexually.

From Salon

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

"Certain temperature conditions may foster all-female populations, which can be overcome through facultative parthenogenesis," he said.

From Salon