Burgess gave three possible origins for the title:
He had overheard the phrase "as queer as a clockwork orange" in a London pub in 1945 and assumed it was a Cockney expression. In Clockwork Marmalade, an essay published in the Listener in 1972, he said that he had heard the phrase several times since that occasion. He also explained the title in response to a question from William Everson on the television programme Camera Three in 1972, "Well, the title has a very different meaning but only to a particular generation of London Cockneys. It's a phrase which I heard many years ago and so fell in love with, I wanted to use it, the title of the book. But the phrase itself I did not make up. The phrase "as queer as a clockwork orange" is good old East London slang and it didn't seem to me necessary to explain it. Now, obviously, I have to give it an extra meaning. I've implied an extra dimension. I've implied the junction of the organic, the lively, the sweet – in other words, life, the orange – and the mechanical, the cold, the disciplined. I've brought them together in this kind of oxymoron, this sour-sweet word." Nonetheless, no other record of the expression being used before 1962 has ever appeared. Kingsley Amis notes in his Memoirs (1991) that no trace of it appears in Eric Partridge's Dictionary of Historical Slang.
His second explanation was that it was a pun on the Malay word orang, meaning "man." The novella contains no other Malay words or links.
In a prefatory note to A Clockwork Orange: A Play with Music, he wrote that the title was a metaphor for "...an organic entity, full of juice and sweetness and agreeable odour, being turned into a mechanism."
In his essay, "Clockwork Oranges," Burgess asserts that "this title would be appropriate for a story about the application of Pavlovian or mechanical laws to an organism which, like a fruit, was capable of colour and sweetness." This title alludes to the protagonist's positive emotional responses to feelings of evil which prevent the exercise of his free will. To induce this conditioning, the protagonist is subjected to a technique in which violent scenes displayed on screen, which he is forced to watch, are systematically paired with positive stimulation  in the form of nausea and "feelings of terror" caused by an emetic medicine administered just before the presentation of the films.