The recency illusion is the belief or impression that a word or language usage is of recent origin when it is long-established.
However, use of the term is not restricted to linguistic phenomena: Zwicky has defined it simply as, "the belief that things you have noticed only recently are in fact recent".
Linguistic items prone to the Recency Illusion include:
- "Singular they": the use of they, them, or their to reference a singular antecedent without specific gender, as in someone said they liked the play. Although this usage is often cited as a modern invention, it is quite old. The usage is found, for example, in Shakespeare.
- The phrase between you and I (rather than between you and me), often viewed today as a hypercorrection, which could also be found occasionally in Early Modern English.
- The intensifier really as in it was a really wonderful experience, and the moderating adverb pretty as in it was a pretty exciting experience: many people have the impression that these usages are somewhat slang-like, and have developed relatively recently. They go back to at least the 18th century, and are commonly found in the works and letters of such writers as Benjamin Franklin.
- "Literally" being used in place of words like "figuratively" or "really" is often viewed as a recent change, but in fact usage dates back to the 1760s. 
- "Aks" as a production of African American English only. Use of "aks" in place of "ask" dates back to the works of Chaucer in Middle English, though typically in this context spelled "ax".
- The word "recency" itself. It is commonly used in consumer marketing ("analyze the recency of customer visits") and many think it was coined for that purpose. But its first known use was in 1612.
- Rickford, John R.; Wasow, Thomas; Zwicky, Arnold (2007). "Intensive and quotative all: something new, something old". American Speech. 82 (1): 3–31. doi:10.1215/00031283-2007-001.
- Zwicky, Arnold (7 August 2005). "Just between Dr. Language and I". Language Log. Retrieved 5 May 2015.
- Merriam Webster's Dictionary of English Usage. Merriam Webster. 1989.
- Shakespeare, William (1594). "Act IV, Scene 3". The Comedy of Errors.
There's not a man I meet but doth salute me / As if I were their well-acquainted friend
- Zimmer, Benjamin. "Literally: a history". Language Log.
- Lippi-Green, Rosina (1997). English with an Accent: Language, Ideology, and Discrimination in the United States (2nd ed.). London: Routledge. ISBN 9780415559102.
- root (14 February 2011). "Recency, Frequency, Monetary Value (RFM) Definition". Investopedia.
- "Definition of RECENCY". Merriam-Webster.com.
- Zwicky, Arnold (17 November 2007). "The word: Recency illusion". New Scientist. 196 (2630): 60. (subscription required)