multiply (v.)

"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, multiple, multiplicate," 1550s, from Latin multiplex "having many folds; many times as great in number; of many parts" (see multiply). As a noun, late 14c. in arithmetic, "a multiple."