The word manifold pertains to something varied or diverse in appearance. It is commonly used to describe a form or character having various forms, features, component parts, or that performs several functions at once. A manifold writer, for example, is an apparatus on which copies of a handwritten document can be made. Between the years 1808 and 1907, this method provided letters, orders, invoices, or documents written in ink to become an exact copy at the same time.
Its meaning has been similar since its earlier uses in a mechanical sense. In 1884 a manifold was known as a pipe or chamber with several outlets with reference to a type of musical instrument mentioned in the old testament: originally a manifold pipe (1857). Today manifold is found to describe components of a system involved in transferring materials from one system to another. For example, an engine part which collects the exhaust gases from multiple cylinders into one pipe is called an exhaust manifold. Hydraulic and inlet manifolds are other engine components all associated with the transfer from one system to another.
The word’s root ‘many’ and suffix ‘fold’ contribute to the overall meaning. Many is “a large or considerable number of persons or things”, contributing to manifolds description of something having various components. Fold meaning to “bring into a compact form by bending and laying parts together” may contribute to the idea of the multiple components and features.
Many and fold are both from before 900; Middle English mani, meni, Old English manig and feald. The word many has a much broader use as in Proto-Indo-Europeam meaning “copious” (cf. Welsh mynych “frequent” and Old Irish magham “gift”). Its partner ‘fold’ is related to Old Norse (Norwegian) faldr; German falt; Gothic falƥs; Greek platos, plos; Latin plus. Most commonly united in English by Latinate double, triple, etc. But still also found in manifold, hundrefold, etc.
In Old English manigfald and West Saxon manigfeald, comes from the root manig and suffix feald. A common Germanic compound (cf. Old Frisian manichfald, MIddle Dutch menichvout, German mannigfalt, Swedish månafalt, Gothic magnafalƥs) and perhaps a borrowed translation from the Latin multiplex, directly related to manifolds use in mathematics meaning a multiple of. Old English also had a verbal form manigfealdian “to multiply, abound, increase.”
Today, manifold, as an adjective, is not commonly used on its own but in participation with propositions ‘by’ (also in, and rarely on). Manifold is easily replaced with its own root ‘many’ and adjectives associated with the root. Many parts of geometry and modern mathematical physics is where the most regular hidden use of manifold is now found because it allows more complicated forms to be described and understood in terms of dimensions and properties.
Although manifold is associated with many different uses the word is often only thought about in terms of one use or the other, never its multiple uses. Knowing its various positions in different sectors such as mechanics, mathematics, and geometry is certainly knowing a "manifold" of uses for the word.
1. Dictionary.com, “fold”, http://dictionary.reference.com/browse/fold?s=t
2. Dictionary.com, “many”, http://dictionary.reference.com/browse/many?s=t
3. Dictionary.com, “manifold”, http://dictionary.reference.com/browse/manifold?s=t
4. Online Etymology Dictionary, “manifold”, http://www.etymonline.com/index.php?allowed_in_frame=0&search=manifold&searchmode=none
5. Wikipedia, Manifold (disambiguation), http://en.wikipedia.org/wiki/Manifold_(disambiguation)
6. Wikipedia, Manifold, http://en.wikipedia.org/wiki/Manifold