orthogenesis

1 of 2

noun

or·​tho·​gen·​e·​sis ˌȯr-thə-ˈje-nə-səs How to pronounce orthogenesis (audio)
: variation of organisms in successive generations that in some especially former evolutionary theories takes place in some predestined direction resulting in progressive evolutionary trends independent of external factors
orthogenetic
ˌȯr-thə-jə-ˈne-tik How to pronounce orthogenesis (audio)
adjective
orthogenetically
ˌȯr-thə-jə-ˈne-ti-k(ə-)lē How to pronounce orthogenesis (audio)
adverb

orthogenetic

2 of 2

adjective

or·​tho·​genetic ¦ȯ(r)thə+ How to pronounce orthogenetic (audio)
: of, relating to, or exhibiting orthogenesis
the theory of orthogenetic evolution—B. R. Redman
orthogenetically
"+ How to pronounce orthogenetic (audio)
adverb

Examples of orthogenesis in a Sentence

Recent Examples on the Web
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.
Noun
The various models proposed for the mechanism of evolution, such as Lamarckian evolution, orthogenesis, and use-disuse, all implied some level of teleology, that there was a directionality inherent in the process. — Mano Singham, Scientific American, 5 Sep. 2021 Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber: a case of degenerative orthogenesis in the absence of sperm competition? — Ed Yong, Discover Magazine, 4 Dec. 2011

Word History

Etymology

Noun

New Latin

Adjective

International Scientific Vocabulary orthogenet- (from New Latin orthogenesis) + -ic

First Known Use

Noun

1895, in the meaning defined above

Time Traveler
The first known use of orthogenesis was in 1895

Rhymes for orthogenesis

See All Rhymes for orthogenesis

Browse Nearby Words

orthoformic ester
orthogenesis
orthogenetic
See all Nearby Words

Cite this Entry

“Orthogenesis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/orthogenesis. Accessed 7 Jul. 2026.

Copy Citation

Medical Definition

orthogenesis

noun
or·​tho·​gen·​e·​sis ˌȯr-thə-ˈjen-ə-səs How to pronounce orthogenesis (audio)
plural orthogeneses -ˌsēz How to pronounce orthogenesis (audio)
: variation of organisms in successive generations that in some evolutionary theories takes place in some predestined direction and results in progressive evolutionary trends independent of external factors
orthogenetic
-jə-ˈnet-ik How to pronounce orthogenesis (audio)
adjective

More from Merriam-Webster on orthogenesis

Britannica.com: Encyclopedia article about orthogenesis

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

Is that lie 'bald-faced' or 'bold-faced'?

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?

Commonly Misspelled Words

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)
See More

Popular in Wordplay

See More

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More

Ten Words Ending with a Silent ‘T’

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

Is that lie 'bald-faced' or 'bold-faced'?

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
hangman letters and game
Hangman Lightning Round Figure out which word fits in the blanks.
See All