The term gibberish was first seen in English in the early 16th century. Its etymology is not certain, but it is generally thought to be an onomatopoeia imitative of speech, similar to the words jabber (to talk rapidly) and gibber (to speak inarticulately).
It may originate from the word jib, which is the Angloromani variant of the Romani language word meaning "language" or "tongue". To non-speakers, the Anglo-Romany dialect could sound like English mixed with nonsense words, and if those seemingly-nonsensical words are referred to as "jib" then the term "gibberish" (pronounced "jibberish") could be derived as a descriptor for nonsensical speech. Another theory is that gibberish came from the name of a famous 8th-century Persian-Arab alchemist, Jābir ibn Hayyān, whose name was Latinized as "Geber." Thus, "gibberish" was a reference to the incomprehensible technical jargon and allegorical coded language used by Jabir and other alchemists.
A discredited alternative theory asserts that it is derived from the Irish word gob or gab (mouth) or from the Irish phrase Geab ar ais (back talk, backward chat). The latter Irish etymology was suggested by Daniel Cassidy, whose work has been criticised by linguists and scholars. The terms geab and geabaire are certainly Irish words, but the phrase geab ar ais does not exist, and the word gibberish exists as a loan-word in Irish as gibiris.
The term gobbledygook was coined by Maury Maverick, a former congressman from Texas and former mayor of San Antonio. When Maverick was chairman of the Smaller War Plants Corporation during World War II, he sent a memorandum that said: "Be short and use Plain English. . . . Stay off gobbledygook language." Later, writing in the New York Times Magazine, he defined gobbledygook as "talk or writing which is long, pompous, vague, involved, usually with Latinized words." The allusion was to a turkey, "always gobbledygobbling and strutting with ridiculous pomposity."