# Genus–differentia definition

A genus–differentia definition is a type of intensional definition, and it is composed of two parts: a genus (or family): An existing definition that serves as a portion of the new definition; all definitions with the same genus are considered members of that genus. the differentia: The portion of the definition that is not provided by the genus. For example, consider these two definitions: a triangle: A plane figure that has 3 straight bounding sides. a quadrilateral: A plane figure that has 4 straight bounding sides. Those definitions can be expressed as one genus and two differentiae: one genus: the genus for both a triangle and a quadrilateral: "A plane figure" two differentiae: the differentia for a triangle: "that has 3 straight bounding sides." the differentia for a quadrilateral: "that has 4 straight bounding sides." The use of genus and differentia in constructing definitions goes back at least as far as Aristotle (384–322 BCE).

## Words

This table shows the example usage of word lists for keywords extraction from the text above.

Word | Word Frequency | Number of Articles | Relevance |
---|---|---|---|

differentia | 5 | 15 | 0.401 |

definition | 7 | 10415 | 0.275 |

differentiae | 3 | 6 | 0.258 |

bounding | 4 | 212 | 0.254 |

genus | 9 | 131771 | 0.21 |