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1. The phenomenon of the existence of isomers.
2. The complex of chemical and physical phenomena characteristic of or attributable to isomers.
3. The state or condition of being an isomer.


1. (Chemistry) the existence of two or more compounds having the same molecular formula but a different arrangement of atoms within the molecule. See also stereoisomerism, optical isomerism
2. (General Physics) the existence of two or more nuclides having the same atomic numbers and mass numbers but different energy states


(aɪˈsɒm əˌrɪz əm)

1. the relation of two or more compounds, radicals, or ions that are composed of the same kinds and numbers of atoms but differ from each other in structural or spatial arrangement.
2. the relation of two or more nuclides that have the same atomic number and mass number but different energy levels and half-lives.
3. the state or condition of being isomerous.
i•so•mer•ic (ˌaɪ səˈmɛr ɪk) adj.
i`so•mer′i•cal•ly, adv.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.isomerism - the state of being an isomer; the complex of chemical and physical phenomena characteristic of isomers
state - the way something is with respect to its main attributes; "the current state of knowledge"; "his state of health"; "in a weak financial state"
References in periodicals archive ?
But her parents have been warned Honey-Rose may not reach adulthood as she also has atrial isomerism - abnormal atria - and pulmonary atresia, meaning the pulmonary valve did not form properly.
Two major types of situs ambiguous (SA) have been described: SA with polysplenia (also known as PS, left isomerism, or bilateral left-sidedness) and SA with asplenia (also known as right isomerism or bilateral right-sidedness).
Abnormal lobation including bronchial isomerism with hyparterial bronchus and unilobar lung may be present.
The geometric isomerism of Organic Chemistry, where "cis" are atoms that, when molecules are divided in half, remain on the same side, and "trans" those remaining on opposite sides.
Atrial flutter in a patient with left isomerism and left-sided inferior vena cava interruption
It should be emphasized that, in addition to the classes to which the constituents belong, other factors must be taken into account in assigning the antibacterial activity, such as isomerism and the synergism between the components.
Due to its highly conjugated structure, lycopene is subject to oxidative degradation and cis-trans isomerism, the latter which is induced by light, temperature or chemical reactions.
Repucci, Electrochemical reduction of nitroaromatics to alinines in base media : effects of positional isomerism and cathode composition, J.
The problems and detailed solutions are arranged in sections such as atomic structure and the periodic table, chemical thermodynamics, the chemistry of groups two and seven, redox chemistry and electrochemical cells, transition metals and their chemistry, isomerism in organic compounds, organic reactions and mechanisms, alcohols and phenol, carboxylic acids and their derivatives, and amino acids.
Coordination compounds of dimethylthallium (III) with 5-(2- pyridinylmethylene) rhodanine or 5-(2-pyridinylmethylene)-2-thiohydantoin: an unusual case of dismotropic isomerism.