The term Ivory Tower originates in the Biblical Song of Solomon (7,4), and was later used as an epithet for Mary. From the 19th century it has been used to designate a world or atmosphere where intellectuals engage in pursuits that are disconnected from the practical concerns of everyday life. As such, it usually carries pejorative connotations of a wilful disconnect from the everyday world; esoteric, over-specialized, or even useless research; and academic elitism, if not outright condescension. In American English usage it is a shorthand for academia or the university, particularly departments of the humanities.
Religious usage 
In Judeo/Christian tradition, the term Ivory Tower is a symbol for noble purity. It originates with the Song of Solomon (7,4) ("Your neck is like an ivory tower"; in the Hebrew Masoretic text, it is found in 7:5) and was included in the epithets for Mary in the sixteenth century Litany of the Blessed Virgin Mary ("tower of ivory", in Latin Turris eburnea), though the title and image was in use long before that, since the 12th century Marian revival at least. It occasionally appears in art, especially in depictions of Mary in the hortus conclusus. Although the term is rarely used in the religious sense in modern times, it is credited with inspiring the modern meaning.
Modern usage 
The first modern usage of "ivory tower" in the familiar sense of an unworldly dreamer can be found in a poem of 1837, "Pensées d’Août, à M. Villemain", by Charles Augustin Sainte-Beuve, a French literary critic and author, who used the term "tour d'ivoire" for the poetical attitude of Alfred de Vigny as contrasted with the more socially engaged Victor Hugo: "Et Vigny, plus secret, Comme en sa tour d’ivoire, avant midi rentrait". At Oxford University, the appearance of the Hawksmoor Towers, twin creamy-white neo-gothic towers at All Souls College, Oxford, the only pure research college at Oxford, epitomize the "ivory tower" of Academe. At the George Washington University, in Washington, DC a residence hall constructed in 2004 was named "Ivory Tower," a decision criticized by some GWU faculty for the reflexive irony of giving the dorm such a moniker.
Henry James' last, unfinished novel, The Ivory Tower, was begun in 1914 and left unfinished at his death two years later. Paralleling James' own dismaying experience of the United States after twenty years away, it chronicles the effect on a high-minded returning upper-class American of the vulgar emptiness of the Gilded Age. "You seem all here so hideously rich," says his hero. Thus, there are two meanings mixed together: mockery of an absent-minded savant and admiration of someone who is able to devote his or her entire efforts to a noble cause (hence "ivory", a noble but impractical building material). The term has a rather negative flavor today, the implication being that specialists who are so deeply drawn into their fields of study often can't find a lingua franca with laymen outside their "ivory towers". Moreover, this problem is often ignored and instead of actively searching for a solution, some scientists simply accept that even educated people can't understand them and live in intellectual isolation.
In Andrew Hodges' biography of Alan Turing, while discussing Turing's 1936-38 stay at Princeton University, he writes that "[t]he tower of the Graduate College was an exact replica of Magdalen College Oxford, and it was popularly called the Ivory Tower, because of that benefactor of Princeton, the Procter who manufactured Ivory soap." William Cooper Procter (Princeton class of 1883) was a significant supporter of the construction of the Graduate College, and the main dining hall bears the Procter name. When asked about the reference, Hodge stated: "The story simply came from my interviewing the graduate students of that epoch, whose names you will find in my narrative. Quite possibly the joke on 'ivory' died with the inter-war period - it has a slightly snobbish feel to it, but perfectly encapsulates the bemusement that the English students would have had at seeing new American money generously deployed in so peculiar a manner."
In Randall Jarrell's essay 'The End of the Line' (1942), Jarrell asserts that if modern poetry is to survive then poets must come down from the "Ivory Tower" of elitist composition. Jarrell's main thrust is that the allusion rich poetry of the modernist period was over-dependent upon reference to other literary works. For Jarrell the Ivory Tower led modern poetry into obscurity.
An ivory tower may also be an entity of "reason, rationality and rigid structures [that] colonizes the world of lived experience," as explained by Kirsten J. Broadfoot in an article about the possibilities of postcolonial organizational communication. This imagined academic community creates an essence of exclusivity and superiority. Broadfoot explains this as a group that “functions like an exclusive club whose membership is tightly controlled by what might be called a ‘dominant frame.’” In an academic sense, this leads to an “overwhelming and disproportionate dominance” of the United States and the Western world. The ivory tower can be dangerous in its inherent privatization of knowledge and intellect. Academics who are seeking “legitimacy for their narratives from the heart end up echoing the sanitized tone of the Master Narrative.” This becomes a cyclical process as intellects collectively defend the “imaginary ivory tower.” 
See also 
- Bull, Marcus Graham (1999). The Miracles of Our Lady of Rocamadour: Analysis and Translation. Woodbridge: Boydell & Brewer. p. 29. ISBN 0-85115-765-3.
- Quinion, Michael (2001-01-13). "On "Ivory Tower"". WorldWideWords.org. Retrieved 2007-04-24. "The origin is the Bible, specifically Chapter 7, Verse 4 of the Song of Solomon, in which Solomon is extolling the beauty of his beloved... Not quite the thing today [...] but it struck a chord with Charles-Augustin Saint-Beuve."
- Hodges, Andrew (1983). Alan Turing: the enigma. New York: Simon & Schuster. ISBN 0-671-49207-1. OCLC 10020685.
- Jarrell, Randall (2008). 'The End of the Line' In Cook, J. ‘Poetry in Theory: An Anthology 1900-2000’. Oxford: Blackwell. ISBN 978-0-631-22554-6.
- Ivory Tower at Wordorigins.org