[pol-ee-mawr-fiz-uhm] Pronunciation Key | 1. | the state or condition of being polymorphous. |
| 2. | Crystallography. crystallization into two or more chemically identical but crystallographically distinct forms. |
| 3. | Biology. the existence of an organism in several form or color varieties. |
| 4. | Genetics. the presence of two or more distinct phenotypes in a population due to the expression of different alleles of a given gene, as human blood groups O, A, B, and AB. |
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.
| pol·y·mor·phism
(pŏl'ē-môr'fĭz'əm) Pronunciation Key
n.
pol'y·mor'phic, pol'y·mor'phous adj., pol'y·mor'phous·ly adv. |
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2006 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
| polymorphism | |
noun | |
| 1. | (genetics) the genetic variation within a population that natural selection can operate on |
| 2. | (chemistry) the existence of different kinds of crystal of the same chemical compound |
| 3. | (biology) the existence of two or more forms of individuals within the same animal species (independent of sex differences) |
polymorphism
(pŏl'ē-môr'fĭz'əm) Pronunciation Key
|
Copyright © 2002 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
polymorphism pol·y·mor·phism (pŏl'ē-môr'fĭz'əm)
n.
- The occurrence of different forms, stages, or types in individual organisms or in organisms of the same species, independent of sexual variations.
- Crystallization of a compound in at least two distinct forms. Also called pleomorphism.
pol'y·mor'phic or pol'y·mor'phous adj.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
polymorphism theory, programming
A concept first identified by Christopher Strachey (1967) and developed by Hindley and Milner, allowing types such as list of anything. E.g. in Haskell:
length :: [a] -> Int
is a function which operates on a list of objects of any type, a (a is a type variable). This is known as parametric polymorphism. Polymorphic typing allows strong type checking as well as generic functions. ML in 1976 was the first language with polymorphic typing.
Ad-hoc polymorphism (better described as overloading) is the ability to use the same syntax for objects of different types, e.g. "+" for addition of reals and integers or "-" for unary negation or diadic subtraction. Parametric polymorphism allows the same object code for a function to handle arguments of many types but overloading only reuses syntax and requires different code to handle different types.
See also generic type variable.
In object-oriented programming, the term is used to describe a variable that may refer to objects whose class is not known at compile time and which respond at run time according to the actual class of the object to which they refer.
(2002-08-08)
Polymorphism
Pol`y*mor"phism\, n. 1. (Crystallog.) Same as Pleomorphism. 2. (Biol.) (a) The capability of assuming different forms; the capability of widely varying in form. (b) Existence in many forms; the coexistence, in the same locality, of two or more distinct forms independent of sex, not connected by intermediate gradations, but produced from common parents.
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