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
tr.v. quelled, quellÂ·ing, quells. 1. To put down forcibly; suppress: Police quelled the riot. 2. To pacify; quiet: finally quelled the children's fears. [Middle English. , to kill, from Old English. ; see gwelÉ- in Indo-European roots .].