A word that encapsulates one or more concepts, sometimes for the sake of referential convenience -- e.g., love and consciousness both collect and gloss a large number of related concepts -- and sometimes just because the writer was vague, using it, they, these, or this instead of a specific referent.
Suitcase word is probably an extension of portmanteau word.
Programmers refer to ad hoc polymorphism as operator or method overloading.