You're reading the public-facing archive of the Category Theory Zulip server.
To join the server you need an invite. Anybody can get an invite by contacting Matteo Capucci at name dot surname at gmail dot com.
For all things related to this archive refer to the same person.
A category is called well powered if the subobjects of any given object form a (small) set.
Is there a standard name for a category where the regular subobjects form a set?
I believe that, yes, "regularly wellpowered" means that.
...which has the unfortunate consequence that a category in which the strong subobjects form a set is called "strongly wellpowered", that being a weaker condition than ordinary wellpoweredness...
Where does the term ‘well-powered’ come from to begin with?
"Power" here surely refers to the powerset...
I presumed so, although I guess ‘small powered’ would have been more clear.
That, to me, sounds more to do with powers-as-in-cotensors.