synaesthesia

noun

1. (countable, uncountable)A neurological or psychological phenomenon whereby a particular sensory stimulus triggers a second kind of sensation.

   “Probably in all of us, though in some men much more distinctly than in others, there exist certain synæsthesiæ or concomitances of sense-impression, which are at any rate not dependent on any recognisable link of association.”

   “[…] R. H. Gault's case of synesthesia in a deaf and blind girl, who could distinguish colors by the sense of smell, […]”

   “Now just as normal perceptions in terms of sense organs different from those stimulated can be interpreted through common past experiences, so it is likely that synæsthesias may be partly explicable in terms of individual experiences.”

   “Into her darkness, a churning synaesthesia, where her pain was the taste of old iron, scent of melon, wings of a moth brushing her cheek.”

2. (broadly, countable, uncountable)The association of one sensory perception with, or description of it in terms of, a different perception that is not experienced at the same time.

   “On a phonemic level, phenomena of synesthesia have often been described and studied. Practically all children and a good many adults—though for the most part adults will deny it—spontaneously associate sounds, whether phonemes or the timbre of musical instruments, with colors and forms.”

   “For one of the enigmatic features of synaesthesia is that, within a given cultural group, the kinds of associations made by different subjects occur according to statistically verifiable recurring patterns. As Jakobson explains, ‘when we ask whether /i/ or /u/ is darker, testing such phonic oppositions as grave vs. acute, some of the subjects may respond that this question makes no sense to them, but hardly one will respond that /i/ is the darker of the two’[…].”

3. (countable, uncountable)A literary or artistic device whereby one kind of sensation is described in the terms of another.

   “Linking moods with colours is one example of synaesthesia. […] As a tool for improving writing, the idea of synaesthesia is versatile and innovative. Why use only visual references to describe visual impressions? Why just describe sounds using sound-related words? Play with cross-matching the senses.”