Also found in: Thesaurus, Medical, Encyclopedia, Wikipedia.
Related to preformation: Preformation theory


1. The act of shaping or forming in advance; prior formation.
2. A theory popular in the 1700s that all parts of an organism exist completely formed in the germ cell and develop only by increasing in size.


1. the act of forming in advance; previous formation
2. (Biology) biology the theory, now discredited, that an individual develops by simple enlargement of a fully differentiated egg cell. Compare epigenesis1


(ˌpri fɔrˈmeɪ ʃən)

1. previous formation.
2. a former biological theory that the individual preexists fully formed in the germ cell and grows from microscopic to normal proportions during the embryo phase.


the theory that germ cells contain every part of the future organism in miniature form, future development being only a matter of increase in size. Cf. epigenesis.
See also: Biology
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.preformation - a theory (popular in the 18th century and now discredited) that an individual develops by simple enlargement of a tiny fully formed organism (a homunculus) that exists in the germ cell
theory - a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"
References in periodicals archive ?
The proposed rules also change the treatment of preformation capital expenditures under Regs.
Another existing exception to the disguised-sale rules is for reimbursements of preformation expenditures (Regs.
Preformation suggests that "nothing more," writes the Abbe Pluche in his 1732 Spectacle de la nature, "will be produced in all the ages to follow .
Plasma insulin decrease causes lipolysis activation from adipose tissue, free fatty acides intensity increase and simultaneously with insulin decrease, glucagon will increase, so this changes is simultaneous while exercising causes more ketogenz activity and liver load and create changes in cholesterol preformation.
They address preformation, including the drug solubility and stability, thermodynamics, rheological aspects of formulation, interfacial science, bioavailability, and mathematical, statistical, and design-of-experiment concepts.
Il y a eu plusieurs acquis: une equipe jeune et competitive, un centre de preformation qui va bientot demarrer, et un stade equipe desormais d'un systeme d'eclairage[beaucoup plus grand que], a-t-il souligne.
Heteroblasty and preformation in mayapple, Podophyllum peltatum (Berberidaceae): Developmental flexibility and morphological constraint.
72) For a brief introduction on the history of preformation, see Ernst Mayr, The Growth of Biological Thought: Diversity, Evolution, and Inheritance (Cambridge, MA: Belknap Press, 1982), 106,645.
The Modern Era: Preformation and Genetic Determinism C.
The story of the Homunculus is based on the popular idea of preformation, which prevailed for a long time.
Caspar Friedrich Wolff's contribution to the concepts of epigenesis versus those of preformation had been the most significant progress towards modern embryology at the end of the 18th century (Perrin and Dupont 2003, Wolff 1768).
This is a good reminder of how long ago the waxes were produced, when epigenesis had yet to fully overcome the idea of preformation.