Why is the ninth month called September?
1540s, from Latin allusionem (nominative allusio) "a playing with, a reference to," noun of action from past participle stem of alludere (see allude). An allusion is never an outright or explicit mention of the person or thing the speaker seems to have in mind.
An indirect reference to some piece of knowledge not actually mentioned. Allusions usually come from a body of information that the author presumes the reader will know. For example, an author who writes, “She was another Helen,” is alluding to the proverbial beauty of Helen of Troy.
in literature, an implied or indirect reference to a person, event, or thing or to a part of another text. Allusion is distinguished from such devices as direct quote and imitation or parody. Most allusions are based on the assumption that there is a body of knowledge that is shared by the author and the reader and that therefore the reader will understand the author's referent. Allusions to biblical figures and figures from classical mythology are common in Western literature for this reason. However, some authors, such as T.S. Eliot and James Joyce, deliberately use obscure and complex allusions that they know few people would understand. Similarly, an allusion can be used as a straightforward device to enhance the text by providing further meaning, but it can also be used in a more complex sense to make an ironic comment on one thing by comparing it to something that is dissimilar. The word is from the late Latin allusio meaning "a play on words" or "game" and is a derivative of the Latin word alludere, meaning "to play around" or "to refer to mockingly."