a condition in which someone experiences things through their senses in an unusual way, for example by experiencing a colour as a sound, or a number as a position in space

A person with synaesthesia may see, for example, the number 2 as a green number and the number 5 as a red number. 有复合感觉的人可能会把2看成是一个绿色号码，5是一个红色号码。