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

Similarly the saphrophytes are classed as obligatory saphrophytes and facultative parasites.

From Project Gutenberg

If a parasite cannot exist outside animal tissues, it is an obligatory parasite; if it can, it is a facultative saphrophyte.

From Project Gutenberg

I have seen this particularly in those cases where facultative divergence also was greater than usual.

From Project Gutenberg

Moreover, the extent of the "facultative" divergence attainable by prisms shows a considerable latitude.

From Project Gutenberg

(b) Both saprophytic and facultative parasitic bacteria agree in requiring non-concentrated food.

From Project Gutenberg