Definition of "synesthesia"

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

1926 July, Paul Campbell Young, “An Experimental Study of Mental and Physical Functions in the Normal and Hypnotic States: Additional Results”, in Margaret F[loy] Washburn, Karl M. Dallenbach, [Isaac] Madison Bentley, Edward G. Boring, editors, The American Journal of Psychology, volume XXXVII, Ithaca, N.Y.: Cornell University, footnote 6, page 346

[S]ynesthetes themselves can provide the indispensable cues to design a structured qualitative questionnaire: color synesthesias and their variations during sexual arousal, direct physical stimulation, and orgasm […] can help scientists differentiate the specific triggers and their characteristics.

2018 April, Helena Melero, “From Pain to Pleasure: A Neuroscientific Approach to Pain-color and Orgasm-color Synesthesias”, in M[ari]a José de Córdoba Serrano, Julia López de la Torre Lucha, Timothy B. Leiden, editors, Actas del ‘VI Congreso Internacional de Sinestesia, Ciencia y Arte + Actividades Paralelas 2018’: Alcalá la Real, Jaén (España), Granada, Spain: Fundació Internacional Artecittà, page 4, column 1