manifold (adj.)

"of many kinds; numerous in kind or variety; diverse; exhibiting or embracing many points, features, or characteristics," Old English monigfald (Anglian), manigfeald (West Saxon), "various, varied in appearance, complicated; many times magnified; numerous, abundant," from manig (see many) + -feald (see -fold). A Proto-Germanic compound, *managafalþaz (source also of Old Frisian manichfald, Middle Dutch menichvout, German mannigfalt, Swedish mångfalt, Gothic managfalþs), perhaps a loan-translation of Latin multiplex (see multiply).

It retains the original pronunciation of many. Old English also had a verbal form, manigfealdian "to multiply, abound, increase, extend;" in modern times the verb meant "to make multiple copies of by a single operation." Related: Manifoldness.

manifold (adv.)

"many times, in multiplied number or quantity," late Old English manigfealde, from manifold (adj.). Old English also had an adverb manigfealdlice "in various ways, manifoldly," from the source of manifold (adj.).

manifold (n.)

in mechanical sense, "pipe or chamber, usually of cast metal, with several outlets," by 1855, a shortening of manifold pipe (by 1845), which originally was used with reference to a type of musical instrument mentioned in the Old Testament. See manifold (adj.). As "pipe running from a carburetor to the cylinders in an internal combustion engine of an automobile," by 1904.

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Definitions of manifold from WordNet
manifold (n.)
a pipe that has several lateral outlets to or from other pipes;
manifold (n.)
a lightweight paper used with carbon paper to make multiple copies;
an original and two manifolds
Synonyms: manifold paper
manifold (n.)
a set of points such as those of a closed surface or an analogue in three or more dimensions;
manifold (v.)
make multiple copies of;
manifold (v.)
combine or increase by multiplication;
Synonyms: multiply
manifold (adj.)
many and varied; having many features or forms;
manifold reasons
our manifold failings
manifold intelligence
Synonyms: multiplex