In 3D, this property is distinct from skewness.
The only "stand-alone" member of Hilbert's axioms is grouped under this heading, and is equivalent to Playfair's axiom. The side-splitter theorem requires that the side-splitter has this property. Two vectors are linearly dependent if they have this property, and such vectors will have a dot product equal to the product of their magnitudes. Spherical and harmonic geometries result if a postulate named for this property is violated. In 3D, this property is distinct from skewness. Trapezoids have one pair of opposite sides with this property. For 10 points, name this property of lines which never intersect.
The only "stand-alone" member of Hilbert's axioms is grouped under this heading, and is equivalent to Playfair's axiom.
parallel [or word forms; or parallel postulate]