WARNING: Antidepressant medications are used to treat a variety of conditions, including depression and other mental/mood disorders. These medications can help prevent suicidal thoughts /attempts and provide other important benefits.
Definition of parallel for Students. 1  1 : a line or surface that lies at or moves in the same direction as another but is always the same distance from it. 2  2 : one of the imaginary circles on the earth's surface running in the same direction as the equator and marking latitude.
A quadrilateral is a parallelogram if: 1  Both pairs of opposite sides are parallel. (By definition). 2  Both pairs of opposite sides are congruent. If they are congruent, they must also be parallel.  One pair of opposite sides are congruent and parallel. Then, the other pair must also be parallel.