Definition of in vivo in US English:

in vivo

adverb & adjective

  • (of a process) performed or taking place in a living organism.

    as adverb ‘fluid transport was measured in vivo’
    The opposite of in vitro
    as adjective ‘in vivo studies in animals’
    • ‘An in vivo human bronchial xenograft model system was used to simultaneously analyze electrolyte and fluid transport defects in fully differentiated human cystic fibrosis (CF) and non-CF proximal airways.’
    • ‘Resin plates were contaminated in vivo upon intraoral use by 10 volunteers for 7 nights.’


Early 20th century: Latin, literally ‘in a living thing’.


in vivo

/ˌin ˈvēvō//ˌɪn ˈvivoʊ/