facultative

[fak-uh l-tey-tiv] /ˈfæk əlˌteɪ tɪv/
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 (opposed to obligate).
5.
of or pertaining to the faculties.
Origin
1810-20; < Neo-Latin facultātīvus. See faculty, -ive
Related forms
facultatively, adverb
nonfacultative, adjective
Examples from the web for facultative
  • Naturally it is not a fixation upon a given strategy, but a facultative flexibility in learning from others.
  • The survivors of the oxygen crisis would have mostly been facultative anaerobes.
  • facultative mimicry: cues for colour change and colour accuracy in a coral reef fish.
  • The facility uses facultative bacteria to nitrify the leachate ammonium to nitrate.
  • Reinsurance contracts are generally categorized as facultative reinsurance or treaty reinsurance.
  • It is the primary facultative organism of the human gastrointestinal tract.
British Dictionary definitions for facultative

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: a facultative parasite can exist as a parasite or a saprotroph Compare obligate (sense 4)
5.
of or relating to a faculty
Derived Forms
facultatively, adverb
facultative in Medicine

facultative fac·ul·ta·tive (fāk'əl-tā'tĭv)
adj.

  1. Capable of functioning under varying environmental conditions. Used of certain organisms, such as bacteria that can live with or without oxygen.

  2. Capable of occurring along various pathways or under various conditions.

fac'ul·ta'tive·ly adv.
facultative in Science
facultative
  (fāk'əl-tā'tĭv)   
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. Compare obligate.