1.a pipe that has several lateral outlets to or from other pipes
2.a lightweight paper used with carbon paper to make multiple copies;
an original and two manifolds
3.a set of points such as those of a closed surface or and analogue in three or more dimensions
4.many and varied; having many features or forms;
manifold reasons
1.make multiple copies of;
multiply a letter
2.combine or increase by multiplication;
He managed to multiply his profits