Answer: A point and a line.
Step-by-step explanation:
There are three undefined terms in geometry which is used to define other terms:
a) Point b) line c) Plane
The definition of parallel lines says that "The two lines are said to be parallel lines if they do not intersect each other at any point. "
Thus, to define parallel lines we have used only two undefined terms i.e. lines and a point .
Hence, the pair of undefined terms is used to define the term parallel lines : Point and Line