Singular
allusion

Plural
allusions

  1. An indirect reference; a hint; a reference to something which is not explicitly mentioned. Its meaning is understood by the reader or the audience.
    1. Next year, I will be doing the Scottish play. The "Scottish play" is an allusion to Shakespeare's Macbeth. (Stage people have a superstition that mentioning its name is bad luck).
    2. The special one is an allusion to José Mourinho, the football manager.