My first thought was 'closure' and after thinking some more I feel that this is the right choice. At least in a Perl context these aren't recognisably objects, and I think that it makes life easier if your choice of names reflects the common syntax of the language.

Perhaps the key question is what will your successors expect these to be called? 'closure' while standard terminology, might not mean enough to them. Of couse you could document it somewhere in your meta-documentation/coding standards...