ekzemplero

Test this one carefully, because it is the band's near miss. It certainly looks like ekzemplo plus -er-, the suffix that names one unit of a mass: sablo gives sablero, a grain of sand, and mono gives monero, a coin. Apply that reading and you get one small piece of an example, which is not what the word means and not a useful thing to mean.

An ekzemplero is one physical unit of an edition: this book off that print run, this issue off that magazine. The mass it is a unit of is the eldono, the edition, not the ekzemplo. So the suffix does not do the work, and the word came into Esperanto whole from Latin exemplar through German and French, where the sense had already settled on a single copy.

What is true is that the two roots are related further back, both off Latin eximere, to take out. That is why the parse gets so close: it points at the right family and the wrong mechanism. Take it as the working test for the whole affix system - decompose only when the pieces actually add up to the meaning.

Use ekzemplero for a copy you can hold and kopio for a reproduction of something: a photocopy, a duplicate file, a forged painting. A library holds ekzempleroj; a photocopier makes kopiojn. For the specimen a scientist puts under glass, the word is specimeno, which is a separate root and not this one.