DictionaryAI

genus

noun
SayJEE-nuhs/ˈd͡ʒiːnəs/UK/ˈdʒiːnəs/

Pluralgenera, genusses, genii

5 meanings of genus

Practice

  1. 1
    rank (biology)nouncountable
    In biology, a rank in classifying living things, below family and above species, or a group of related species at that rank; its name begins a two-part scientific name.

    Lions, tigers and leopards all belong to the genus Panthera.

    Botanists moved the plant to a new genus after DNA tests revealed its closest relatives.

    Note

    The shortened use lets genus stand for the genus name, the first word of a binomial. That name can stand alone, as Magnolia does for every magnolia, while the second word of a species name is never used without its genus.

    Checked 1 Nov 2026 · 3 facts

  2. 2
    nouncountable
    A group or class of things that share common attributes.
    Recollection is one of a whole genus of effects which are more or less peculiar to the phenomena that we naturally call "mental."
    1945, Bertrand Russell, A History of Western Philosophy

    Similarclass, category, kind, type

    Note

    Latin genus meant birth, origin, a race, a sort or kind, from the root of gignō, "to beget", and this general sense stays closest to it. The same Latin word gave English gender and genre, and kin is a distant relative. Bertrand Russell, in A History of Western Philosophy (1945), calls recollection one of "a whole genus of effects".

    Checked 30 Oct 2026 · 6 facts

    • Latin genus had the stated meanings and shares its root with gignō, meaning 'to beget'. en.wiktionary.org
    • English gender derives ultimately from Latin genus. en.wiktionary.org
    • English genre derives ultimately from Latin genus. en.wiktionary.org
    • Kin is etymologically related to genus. en.wiktionary.org
    • Bertrand Russell wrote A History of Western Philosophy, first published in 1945. en.wikipedia.org
    • Russell describes recollection using the exact phrase 'a whole genus of effects'. russell-j.com
  3. 3
    mathnoun
    A natural number giving any of several related measures of how complex a particular manifold or graph is.

    A sphere has genus zero, while a torus has genus one.

    The genus of a graph is the smallest genus of a surface on which it can be drawn without any edges crossing.

    Note

    For a closed orientable surface the genus counts its handles, the holes that pass all the way through, so a doughnut and a coffee mug share a genus of one. Topology, graph theory and algebraic geometry each define their own version, which is why the word usually comes with its object named: the genus of a surface, the genus of a graph.

    Checked 30 Oct 2026 · 4 facts

    • The genus of a closed orientable surface counts its handles. jeffe.cs.illinois.edu
    • The holes being counted are through-holes, rather than hollow interiors or indentations. en.wikipedia.org
    • A doughnut and an ordinary coffee mug with one handle both have genus one. ics.uci.edu
    • Topology, graph theory and algebraic geometry have related definitions of genus. mathworld.wolfram.com

Less common meanings

  1. 4
    logicnouncountable
    In a definition, the broader category to which the defined concept belongs.

    A classical definition names the genus first and then the features that set the term apart within it.

    If a sofa is defined as a long upholstered seat, then seat is the genus.

    Note

    A classical definition pairs the genus with a partner, the differentia: the features that set the defined thing apart from everything else in its class. In "a triangle is a polygon with three sides," polygon is the genus and with three sides is the differentia. Name the class, then narrow it; that is the whole recipe.

    Checked 30 Oct 2026 · 3 facts

    • A classical genus–differentia definition combines a broader class with features distinguishing the defined thing from other members of that class. people.math.wisc.edu
    • A triangle is a polygon with three sides. en.wikipedia.org
    • In the example, polygon supplies the genus and having three sides supplies the differentia. en.wikipedia.org
  2. 5
    noun
    One of the types of tuning or intonation used within a tetrachord in ancient Greek music.

Practice

Can you tell the meanings of genus apart? Answer 3 quick questions from this page, or write your own sentence and AI will check it.

Origin

Latin genus, which covered "birth, origin, a race, sort, kind," was taken directly into English. It is built on the root gen- found in Latin gignō ("to beget, produce"). Gender and genre are doublets, and kin is a more distant relative.

Checked 1 Nov 2026 · 6 facts