Both Uses

manifold
in
Song of Myself
(Auto-generated)

I pass death with the dying and birth with the new-wash'd babe, and
am not contain'd between my hat and boots,
And peruse manifold objects, no two alike and every one good,
The earth good and the stars good, and their adjuncts all good.†
*
In vain the speeding or shyness,
In vain the plutonic rocks send their old heat against my approach,
In vain the mastodon retreats beneath its own powder'd bones,
In vain objects stand leagues off and assume manifold shapes,
In vain the ocean settling in hollows and the great monsters lying low,
In vain the buzzard houses herself with the sky,
In vain the snake slides through the creepers and logs,
In vain the elk takes to the inner passes of the woods,
In vain the razor-bill'd auk sails far north to Labrador,
I follow quickly, I ascend to the nest in the fissure of the cliff.†

Definitions:

(1) (manifold as in: reasons are manifold)
many and varied
(2) (meaning too rare to warrant focus)
Manifold can also be used as a noun to refer to a pipe that has several lateral outlets to or from other pipes; such as "the intake manifold of an engine." It can also refer to a concept in differential geometry.