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What is the difference in usage between these three apparently-synonymous words: duplicate, replicate, and reduplicate. (Definitions from ODO)

duplicate: make or be an exact copy of
replicate: make an exact copy of; reproduce
reduplicate: repeat or copy so as to form another of the same kind

Why is it correct to say that the results of an experiment are replicated, but copies of a thesis are duplicated?

How should I discuss the following:

Procedure X should work as though each node i in a graph were replaced with v_i identical copies of it.

Have the nodes been replicated, duplicated, or reduplicated? Should I reserve duplication for doubling in quantity?

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Consult your local dictionary. –  Mahnax May 25 '12 at 5:06
@Mahnax: I did, and I couldn't distinguish the definitions. –  Neil G May 25 '12 at 6:08
Edited to make less "general reference" (I hope) –  Andrew Leach May 25 '12 at 6:48
I think, "duplicate" means more to make a copy (in case of the thesis e.g. to scan and print again) while "replicate" is more to do something again, that is, regarding the experiment, to repeat the test. For instance a replica can differ in result from the original (a replica of a artwork) –  Em1 May 25 '12 at 6:59
@AndrewLeach: Thanks Andrew. I've added the sentence I'm trying to write as well. I didn't think it would be useful, but maybe it will improve the question. –  Neil G May 25 '12 at 7:19

4 Answers 4

up vote 4 down vote accepted

If you replicate a finding, you may have come to the conclusion independently.

If you duplicate a finding, you have not come to the conclusion independently but have restated it.

Reduplication should be used only when something has been duplicated more than one time. If something has been duplicated exactly once, it is simply duplication.

Since your example sentence mentions "identical copies," duplication is more applicable than replication. Reduplication could be used if the procedure replaced the same nodes more than once but that doesn't appear to be the case here.

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Replicate is used in the following sentences, where duplicate should not be used.

It might be impractical to replicate eastern culture in the west.

Interleukin-16 prevents the virus from replicating itself.

These findings have been replicated by Atwood and Jackson.

When talking of genetic material, or a living organism, you don't say duplicate except in the case you mean double as in "the normal amount of DNA has been duplicated thousands of times."
When talking of scientific experiments, you could say "their experiment duplicated work already done," but in that case duplicate would mean "do something again unnecessarily."

In the example you make, I would say the nodes are duplicated. Re-duplicated would mean "duplicating something that duplicates something else": I duplicate node A to create node B, and I duplicate node B to make node C.

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Here's how I look at it, but I could be wrong.

Duplicate: To make one exact copy of something.

Replicate: To make a general copy or copies of something, one or more times. ie: a printed copy of an original painting. (Make a replica)

Reduplicate: To make one or more exact copies of a duplicate. To make more than one exact copy of something.

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I don't see any restriction to a single duplicate (possible etymology aside). For example before photocopiers became widespread a less sophisticated process of producing multiple copies from an original was called duplicating using a machine called a duplicater. –  Chris H Feb 20 at 8:51

"Duplicate" may also be employed per this discussion, tangentially, as an adjective or noun.

Adj. -- I will produce a duplicate blueprint.

Noun -- The second blueprint is a duplicate of the first.

Attempting to employ "Replicate" thus, sounds/read quite stilted to the native ear/eye.

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protected by tchrist Mar 1 at 18:36

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