Definition of endosymbiont in US English:

endosymbiont

noun

Biology
  • See endosymbiosis

    • ‘Several species of asexual endosymbionts have experienced accelerated rates of molecular evolution relative to their free-living relatives.’
    • ‘Genes have recently been discovered in the nuclear genomes of these that appear to have been introduced by an ancestral endosymbiont.’

Pronunciation

endosymbiont

/-ˈsimbī-/