As is well known, “camp” in Latin is castra, neuter plural decl2. This also means “forts” and is often found referring to Roman army camps.
(1) Is it the only word usable when referring to a few travellers making an ordinary unfortified night camp?
(2) In postclassical and mediaeval Latin, how often is the wrong form castram, castrae found? Some people have likely made that mistake, because castra got into the Anglo-Saxon language as sēo ceaster = “the (Roman) town”, feminine singular, from which “-chester” and similar at the ends of some English placenames.
You’re undoubtedly right about the transgendering of castra, as evidenced by Anglo-Saxon. In fact, Lewis and Short cite an instance of feminine castra, -ae in a fragment of the tragedian L. Accius (or Attius), whose dates are 170 - cir. 85 BCE (according to the Oxford Latin Dictionary). So this was already happening in the pre-classical period, and may well have been widespread in popular speech at an early date.
You might consult the Dictionary of Medieval Latin from British Sources, if you have access to a large reference library.
But, if e.g. some boys went on a camping holiday with tents, and afterwards at school were called on to describe it in Latin, likely many boys here have trusted their Latin textbook’s vocabulary list and called their (unfortified) camp castra. But what would the correct Latin word be here?
Preview: Re: Camp
Traupman gives aestiva, -orum (summer camp) as opposed to hiberna, -orum (winter camp/quarters). Both neuter plurals like castra. But you’d be converting an ancient military term to modern civil usage (‘conflabunt gladios suos in vomeres’ - they will beat their swords into plowshares).
