Spelling aquaeductus together

Question

The word aquaeductus can also be spelled aquae ductus or ductus aquae, possibly with the plural aquarum (see Lewis and Short). Spelling it separately in either order makes sense, as the aqueduct is a conductor (ductus) of water (aquae). But why is it also spelled together in classical Latin?

To be more precise, is there classical evidence for spelling aqueductus as a single word? If yes, what does that even mean? Word boundaries were not as clearly defined and marked as today, but they were not entirely non-existent either. Perhaps this is just a later editorial decision and has nothing to do with classical spelling, but it's hard for me to judge.

Answer 1

The "slam dunk" evidence we'd want in a case like this is an inscription with word boundaries that does not separate aquaeductus.

Though I can't find any such evidence after a brief search, one piece of indirect evidence makes the supposition likely, especially given the fact that scholars much smarter than me have adopted the convention of spelling it as a compound. This indirect evidence is that the word is likely an imitation of the Greek equivalents: ὑδραγωγία or ὑδραγώγιον.

Here, unlike in Latin, the compounding behavior is much more evident. Latin wasn't quite as productive as Greek with compounds of this kind, but it certainly seems to be a point in favor!