What is the origin of the word allusion?

An allusion, as in an implicit mention of the person or thing the speaker has in mind, is derived from Latin.

Allusion was added to the English vocabulary in the 1540s, from the Latin allusionem (the nominative form of allusio). This was a noun based on the past participle of the Latin verb, alludere "to play, sport, joke, jest".

Alludere can be further attributed to the Latin prefix ad- "to" (which became al- to complement the starting consonant of the second part) and the verb ludere "to play".