from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. An atom, radical, or group substituted for another in a chemical compound.
  • adj. Of or relating to such an atom or group.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. any atom, group, or radical substituted for another, or entering a molecule in place of some other part which is removed

from the GNU version of the Collaborative International Dictionary of English

  • n. Any atom, group, or radical substituted for another, or entering a molecule in place of some other part which is removed.

from The Century Dictionary and Cyclopedia

  • n. That which substitutes; in chem., an atom or atomic group which takes the place of another atom or group present in the molecule of the original compound. Thus in the compounds methane (CH4) and methyl alcohol (CH3OH), OH is said to be the substituent.


Latin substituēns, substituent-, present participle of substituere, to substitute; see substitute.
(American Heritage® Dictionary of the English Language, Fourth Edition)


  • Would the substituent fractions all have faced the same exact problems?

    Matthew Yglesias » Too Big to Exist

  • The other contribution is the synthesis of liquid crystalline conjugated polymers by replacing the hydrogen atom bonded to polyacetylene with a substituent having liquid crystalline nature as the side chain.

    Hideki Shirakawa - Autobiography

  • Deci, această secţiune este prezentat aici ca un substituent, un monument mici pentru a optimismul meu. »2003» October

  • My first scientific paper in 1961 reported an additivity rule for substituent induced shifts of proton NMR signals in steroid derivatives.

    Jean-Marie Lehn - Autobiography

  • Biogenesis becomes reproduction; re - production becomes cellular; cell division becomes mitotic; chromosomes split longitudinally, or put more accurately, they replicate themselves, since each new chromosome is no half-chromosome but a chromosome entire; and finally, the substituent elements of the chromosomes, whether visible chromatids or invisible genes, are held likewise to replicate themselves.


  • The complementary substances or substituent groups with which these nuclei are more or less firmly combined in nature exert a stabilizing and perhaps otherwise favorable influence on the curative nucleus, but do not themselves possess the vitamine type of physiological potency.

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  • All alcohols carry a hydroxyl substituent (- OH), so they too have oxygen atoms in them.

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  • These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent. - Articles related to Plants give up some deep secrets of drought resistance

  • "The record, however, shows no discernible reason for a skilled artisan to begin with lansoprazole only to drop the very feature, the fluorinated substituent, that gave this advantageous property."

    Patent Law Blog (Patently-O)

  • In particular, the court noted that it would not make sense to drop trifluroethoxy from the prior art - since it is that substituent that activated Lansoprazole.

    Patent Law Blog (Patently-O)


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