A line and a plane are parallel if they do not intersect.

Kern, W. F. and Bland, J. R. Solid Mensuration with Proofs, 2nd ed. New York: Wiley, p. 9, 1948.

CITE THIS AS:

Weisstein, Eric W. "Parallel Line and Plane." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/ParallelLineandPlane.html