A technique common in Symbolist verse whereby the writer tries to bring many senses into play, for example describing sounds as colours, or colours as tastes. Whilst synaesthesia may be found occasionally in earlier writing, its programmatic use probably begins with Baudelaire's Les Fleurs du Mal (1857) and then radiates through Rimbaud and into English verse via Swinburne and Yeats. Here is an example from James Joyce's Portrait of an Artist as a Young Man (1916): “He listened to their cries: like the squeak of mice behind the wainscot: a shrill twofold note. But the notes were long and whirring, unlike the cry of vermin, falling a third or a fourth and trilled as the flying beaks clove the air. Their cry …
Editors. "Synaesthesia". The Literary Encyclopedia. First published 01 November 2001; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1084, accessed 20 April 2015.]