Allusion
Allusion is a figure of speech, in which one refers covertly or indirectly to an object or circumstance from an external context.
It is left to the audience to make the connection.
It is not possible to predetermine the nature of all the new meanings and inter-textual patterns that an allusion will generate.
- says Wikipedia
Allusion is also the name of the WordPress theme in use on my personal WordPress site
I forked it from Sage