Definition of cloaca in US English:


nounPlural cloacae

  • 1A common cavity at the end of the digestive tract for the release of both excretory and genital products in vertebrates (except most mammals) and certain invertebrates. Specifically, the cloaca is present in birds, reptiles, amphibians, most fish, and monotremes.

    • ‘After males deposit spermatophores onto the cloaca of females, up to 150 eggs are laid on mud near water.’
    • ‘Unlike we humans, the chicken has a single sexual and excretory orifice, the cloaca.’
    • ‘Instead, males deposit spermatophores on the substrate and females pick up these spermatophores with their cloaca later.’
    • ‘The bursa of Fabricius is an organ located just beside the cloaca.’
    • ‘Salamanders were measured from the tip of the snout to the anterior end of the cloaca.’
    1. 1.1archaic A sewer.
      • ‘The cloaca maxima was the sewer system built in the sixth or seventh century BC, by one of the kings of Rome.’


Late 16th century (in the sense ‘sewer’): from Latin, related to cluere ‘cleanse’. The first sense dates from the mid 19th century.