Definition of geminal in US English:



  • Denoting substituent atoms or groups, especially protons, attached to the same atom in a molecule.

    • ‘The fellow doing it was down the hall from me in graduate school, and he was doing an obscure reaction which forms a geminal dinitrile, which themselves are rather obscure compounds.’
    • ‘Compounds in which two hydroxyl groups are attached to the same carbon atom (geminal diols) normally cannot be isolated.’
    • ‘Particularly in the pathological examination, we discovered that it could activate and proliferate cells in lymph follicles, geminal centre, paracortical zone and medullary cord of lymph nodes.’
    • ‘This showed a reactive lymph node with prominent geminal centres and focal areas in keeping with necrotising granulomata.’


1960s: from Latin geminus ‘twin’ + -al.