facultative
adjective
fac·ul·ta·tive
ˈfa-kəl-ˌtā-tiv 
British -tə-tiv
1
a
: of or relating to the grant of permission, authority, or privilege
facultative legislation
b
: optional
2
: of or relating to a mental faculty
3
a
: taking place under some conditions but not under others
facultative diapause
b
: exhibiting an indicated lifestyle under some environmental conditions but not under others
facultative anaerobes
facultatively
adverb
Examples of facultative in a Sentence
Recent Examples on the Web
For the cancer patients, their gut showed a lower amount of beneficial bacteria and a higher amount of facultative pathogens.
—
Stephanie Edwards, Discover Magazine, 13 June 2025
After heading several facultative roles at the company, Elamin serves as the head of facultative for Aon Reinsurance Solutions for the Middle East, Africa and Turkey.
—Mckinley Franklin, People.com, 8 Jan. 2025
Unlike the Queensland lungfish, which is a facultative air-breather, the South American lungfish must breathe air to survive.
—Scott Travers, Forbes, 15 Sep. 2024
This is all speculative, but the hypothesis that Dudgeon is playing with is that, for some vertebrates, facultative parthenogenesis might be like the evolutionary equivalent of a Hail Mary pass.
—Byrd Pinkerton, Vox, 12 June 2024
Discovery of facultative parthenogenesis in a new world crocodile
Biology Letters.
—Cody Cottier, Discover Magazine, 22 Mar. 2024
Advertisement Booth wanted to prove that the stillborn crocodile was created through facultative parthenogenesis.
—Kyle Melnick, Washington Post, 9 June 2023
Advertisement Most facultative parthenogenesis discoveries have occurred in the past two decades as DNA testing has evolved.
—Kyle Melnick, Washington Post, 9 June 2023
This occurred through facultative parthenogenesis, a form of asexual reproduction.
—Kyle Melnick, Washington Post, 9 June 2023
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Stephanie Edwards, Discover Magazine, 13 June 2025
After heading several facultative roles at the company, Elamin serves as the head of facultative for Aon Reinsurance Solutions for the Middle East, Africa and Turkey.
—Mckinley Franklin, People.com, 8 Jan. 2025
Unlike the Queensland lungfish, which is a facultative air-breather, the South American lungfish must breathe air to survive.
—Scott Travers, Forbes, 15 Sep. 2024
This is all speculative, but the hypothesis that Dudgeon is playing with is that, for some vertebrates, facultative parthenogenesis might be like the evolutionary equivalent of a Hail Mary pass.
—Byrd Pinkerton, Vox, 12 June 2024
Discovery of facultative parthenogenesis in a new world crocodile
Biology Letters.
—Cody Cottier, Discover Magazine, 22 Mar. 2024
Advertisement Booth wanted to prove that the stillborn crocodile was created through facultative parthenogenesis.
—Kyle Melnick, Washington Post, 9 June 2023
Advertisement Most facultative parthenogenesis discoveries have occurred in the past two decades as DNA testing has evolved.
—Kyle Melnick, Washington Post, 9 June 2023
This occurred through facultative parthenogenesis, a form of asexual reproduction.
—Kyle Melnick, Washington Post, 9 June 2023
Cite this Entry
“Facultative.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/facultative. Accessed 21 Jul. 2025.
Copy CitationMedical Definition
facultative
adjective
fac·ul·ta·tive
ˈfak-əl-ˌtāt-iv
1
: taking place under some conditions but not under others
facultative parasitism
2
: exhibiting an indicated lifestyle under some environmental conditions but not under others
facultative anaerobes
facultatively
adverb
Love words? Need even more definitions?
Merriam-Webster unabridged
Share