When a geometry is described by a set of axioms, the notion of a line is usually left undefined (a so-called primitive object). The properties of lines are then determined by the axioms which refer to them.
Definition of mull 1: friable forest humus that forms a layer of mixed organic matter and mineral soil and merges gradually into the mineral soil beneath 2: a finely powdered solid especially in a suspension
quill noun [C]. âº a âlong, âsharp âpoint on a porcupine, or a âlarge âfeather with the end âcut to a âsharp âpoint that was used, esp. in the past, as a âpen.(Definition of quill from the Cambridge Academic Content Dictionary Â© Cambridge University Press).See all translations.uill noun [C]. âº a âlong, âsharp âpoint on a porcupine, or a âlarge âfeather with the end âcut to a âsharp âpoint that was used, esp. in the past, as a âpen.