Definition of -gen in US English:

-gen

combining form

  • 1Chemistry
    Denoting a substance that produces something.

    ‘oxygen’
    ‘allergen’
  • 2Botany
    Denoting a substance or plant that is produced.

    ‘cultigen’

Origin

Via French -gène from Greek genēs ‘-born, of a specified kind’, from gen- (root of gignomai ‘be born, become’, genos ‘a kind’).