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. ( 2 By definition). 3  Or: 4  Both pairs of opposite sides are congruent. 5  If they are congruent, they must also be parallel. 6  Or: 7  One pair of opposite sides are congruent and parallel.