Definition of penetrant in US English:



  • (of a gene or group of genes) producing characteristic effects in the phenotypes of individuals possessing it.

    • ‘In a primary screen, we collected mutant lines in which the test females showed a significantly more penetrant sterile phenotype than did females of the sensitive background alone.’
    • ‘Many of these women will [may] not have a family history that suggests the presence of a highly penetrant breast cancer susceptibility gene.’
    • ‘Because of the difficulties associated with performing genetics on partially penetrant mutations, this mutant will not be discussed further in this paper.’
    • ‘Of the 230 mutants, 55 fell into the first class and we continued the characterization of 36 of these mutants that had highly penetrant mutant phenotypes.’
    • ‘This lethality was incompletely penetrant in gametes and completely penetrant postfertilization.’


  • A substance that can penetrate cracks, pores, and other surface defects.

    • ‘Unique to such a thick oil are penetrants designed to reach deep within to all points of the chain.’
    • ‘Use latex products, penetrants, or breathable epoxy generic materials designed to reduce the emission of water vapor from the slab.’
    • ‘Most adjuvants (emulsifiers, penetrants, and safeners) are potential skin and eye irritants of very low toxicity.’
    • ‘There are basically two types of water repellents: films and penetrants.’