Definition of nucleolus in English:


nounPlural nucleoli

  • A small dense spherical structure in the nucleus of a cell during interphase.

    • ‘Some cells had conspicuous nucleoli, and others had cytoplasmic clearing.’
    • ‘Microscopically, large neoplastic lymphoid cells with prominent nucleoli and frequent mitotic figures occlude small vessel lumina.’
    • ‘Mature red blood corpuscles are membrane bound and normally devoid of a nucleus, nucleolus, cell organelles, and inclusions.’
    • ‘The tumor cells were arranged in trabecular and solid patterns with nuclear pleomorphism, prominent nucleoli, and scant basophilic cytoplasm.’
    • ‘As the cells separated their chromosomes, the nucleolus also appeared to segregate asymmetrically between mother and daughter cells, with the majority in the mother.’


Mid 19th century: from late Latin, diminutive of Latin nucleus ‘inner part, kernel’ (see nucleus).