## Which undefined terms are needed to define parallel lines?

The undefined terms needed to define parallel lines areĀ

**‘lines’ and ‘points.****‘**## Undefined Terms in Geometry

Words used in geometry can be categorized as defined terms and undefined terms. An undefined term is a geometrical word that we cannot describe using other geometrical terms, whereas a defined term is a geometrical word or phrase that we can describe using other geometrical terms. We can use undefined terms to define defined terms.